One question. One clear answer.

Normal ride recording with iPhone GPS, live values and ride statistics remain free, as does the 0–100 km/h or 0–60 mph sprint measurement. One Garage vehicle, the Apple Watch remote, optional Race Training with heart rate, Live Activity, naming and deleting rides, the map view, Race Summary and importing existing Track4Facts backups are also free. The lock never deletes previously saved data.

The Full Version unlocks the complete lap/racing mode with tracks, start/finish, sectors, live delta and lap times. This includes the lap list, sector view and lap comparison in History. It also includes distance timing, custom sprint ranges, external Bluetooth GPS receivers, the other charts, sprint comparison, vibration analysis, Ghost Lap, Replay, GPX/CSV export, complete backup export and additional Garage vehicles. It is a one-time purchase with no subscription; earlier customers who bought the paid app keep the Full Version automatically.

After you start recording, Track4Facts continues in the background, including while the screen is locked. Valid GPS samples are used for speed, top speed, distance and average speed. The app also determines ride duration, stops and, when vertical accuracy is sufficient, elevation difference. During recording, it also saves time-stamped iPhone motion data with the ride: acceleration and, where available, gravity direction and rotation rate. This happens regardless of which analysis is currently open.

Sprint timing runs alongside the normal ride recording; in the Full Version this also applies to enabled distance targets. The measurement page currently visible does not change what is measured for the active ride. In Lap mode, completed laps and their sector times—when captured completely—are stored as well. When optional Race Training is enabled on a paired Apple Watch and Health access is granted, time-aligned heart-rate values are stored too.

No. A normal ride may begin while the vehicle is already moving. As soon as several coherent, plausible GPS samples confirm motion, speed, distance, top speed and the other ride statistics update.

Only measurements that require a real standing start—such as 0–100 or distance from zero—remain locked until the app observes a stable standstill during the same recording.

iPhone GPS needs no extra hardware and reaches Track4Facts through Core Location. It provides position, GPS speed and normally horizontal, vertical, speed and course accuracy. Its update rate is controlled by the system and is typically lower or more variable than that of an external performance receiver. Core Location does not expose satellite count or pDOP to the app.

Supported Bluetooth receivers are XGPS150, XGPS160 and Dragy Lite. XGPS provides a 2D/3D fix, speed, course, battery and, where available, WAAS/DGPS. The XGPS SDK used here does not expose per-sample accuracy values, satellite count or pDOP in every update, so those diagnostics may show “–”. Dragy Lite additionally provides horizontal and vertical accuracy, speed and course accuracy, satellite count and pDOP. Its update rate can be set to 10, 20 or 25 Hz in GPS diagnostics.

The configured position- and speed-accuracy limits apply to iPhone and Dragy because both provide those values. For XGPS, Track4Facts instead validates the fix, age, continuity and plausibility of the samples. A higher rate can resolve threshold and line crossings more finely in time, but is not automatically more accurate: reception, antenna position, satellite geometry, reflections and fix quality remain decisive.

External GPS receivers require the Full Version. XGPS150 or XGPS160 must be connected to the iPhone; the app automatically searches for a powered-on Dragy Lite and reconnects it after an interruption. If a Dragy has not yet been prepared for performance operation, its one-time GNSS configuration and restart can take about 45 seconds. Use only one external receiver at a time.

The source is fixed when a ride starts. If a supported receiver is connected then and the Full Version is active, Track4Facts uses its GPS; otherwise iPhone GPS remains active. A receiver that connects during a ride deliberately takes over only on the next recording. If the active external receiver drops during a ride, ordinary ride recording falls back to iPhone GPS; a running sprint or distance attempt is interrupted so no time is interpolated across two different sensors.

The source label below the record button shows which source is actually active before and during the ride. Apple Watch is only a display and remote and does not change that selection.

The GPS indicator below the record button remains active even when no recording is running. Tap it to inspect source, sample age, position, accuracy values, speed, course, fix quality and—when using an external receiver—its battery. Only Dragy Lite also shows its selectable update rate and the satellite and pDOP values it supplies.

Green means a current position and speed fix suitable for the active source is available. Yellow indicates an existing but limited or not yet current fix. For iPhone GPS the indicator can be red or unavailable when location permission is missing or no fix exists; for a connected external receiver the compact source label remains limited while waiting for a fix. The detail view identifies whether position, speed, accuracy or freshness is missing.

A “–” means the active source does not provide that value; it is neither a numerical zero nor automatically a fault. This is normal for satellite count and pDOP on iPhone and for several individual accuracy values on XGPS. Dragy Lite supplies them when they are present in its fix. The source-specific fix check—not the sheer number of populated rows—is what decides usability.

GNSS supplies both position and speed as estimates. Satellite geometry, the atmosphere and reflected signals can therefore cause small non-zero speeds even at a standstill. Track4Facts uses the speed reported by the iPhone or external receiver; it does not generally derive live speed from two consecutive positions. GNSS receivers can obtain velocity from sources including the Doppler shift of satellite signals. Apple does not specify how Core Location forms its value internally. The familiar √2 · σ / Δt model applies only when speed is calculated from two independent position estimates, so it does not explain every displayed speed error.

Track4Facts uses hysteresis: one low value does not determine standstill or motion. With iPhone GPS, consecutive speeds, displacement, horizontal accuracy and available motion information are classified together. XGPS and Dragy Lite use short time-based confirmation windows for their faster sample streams; Dragy accuracy values are additionally checked against the configured limits. Confirmed standstill is normalised to zero for display and 0–X logic, while original timestamps remain available for later interpolation.

With iPhone GPS, reported low speeds remain visible while braking even before the stop is confirmed. External receivers buffer the short transition sequence before changing state. This keeps sources with different rates stable without treating one noisy value as a start or stop.

The 3 km/h tolerance is the same for every source, but confirmation reflects its data type and rate. With iPhone GPS, at least two low, positionally stable samples confirm the transition from motion to standstill; genuine low speeds remain visible meanwhile. XGPS and Dragy Lite confirm low values over a short time window containing several plausible samples. Only that confirmed transition increments the stop counter, produces canonical standstill and may arm another attempt.

Track4Facts requests positions continuously during recording, including at standstill. If Core Location exceptionally reports no speed, several tightly clustered iPhone positions over at least two seconds may infer standstill. This fallback may re-arm distance timing but never a 0–X sprint. External receivers instead require a valid speed fix.

Confirmed iPhone standstill points remain in the route and exports as diagnostic evidence. For high-rate external receivers, “Save every point from external receivers” controls how densely valid points are persisted; live measurement still processes the incoming stream independently.

In Settings you can follow the iPhone system units or choose Metric or Imperial. Inputs, speedometer, routes and result lists then use km/h and metres/kilometres or mph and feet/miles.

Track4Facts always stores speeds internally in km/h and distances in metres. Changing units later therefore changes presentation only, never the recorded measurements.

The quality grade describes confidence in the input data, not driving performance. Green means accuracy, sample intervals and plausibility checks remained in the good range. Yellow marks a numerically valid result with increased uncertainty due to a larger sample gap or limited fix quality. The least favourable segment quality determines the overall attempt grade.

A missing value is not a numerical zero. It means the measurement conditions were incomplete—for example target not reached, no confirmed standstill, start threshold not approached from below, data gap, rejected fix or implausible jump. Status and failure reason are stored with the ride.

Measurement uncertainty has at least two components: spatial uncertainty of position and temporal uncertainty caused by sampling rate. Plausibility filters reduce gross outliers, confirmation windows stabilise state transitions, and linear interpolation reduces the rounding error that would arise if only the next GPS sample counted as the threshold. These methods improve the estimate but cannot create information the receiver did not measure.

Results still depend on reception, antenna placement, sky visibility, device and update rate. Tunnels, urban canyons, reflections and long gaps increase uncertainty. The app is not an officially calibrated instrument. For comparable attempts, keep source and mounting position constant, use similar conditions and consider the stored quality grade.

Without interpolation, assigning an event to the next sample would delay it by at most one sample spacing Δt = 1/f. Δt/2 is the mean only if the true crossing phase is uniformly distributed between samples. The possible sampling component is up to 1 s at 1 Hz and 0.04 s at 25 Hz. For a line crossing, a position error Δs along the direction of travel shifts time by approximately Δs/v; at 100 km/h, 1 m corresponds to about 0.036 s. These examples are not total error bounds: receiver noise, latency and model error also contribute.

Secure the smartphone before driving without obstructing view, controls or airbags. Do not operate the app while driving. Perform performance measurements only on private property, on closed courses, or in areas expressly permitted for such driving.

Never force a measurement: safety, traffic laws, visibility, weather and traffic conditions always come first.

In Video Studio, open the Custom card under Make it yours. Use the tiles to switch speed, lap/time, track, G-circle, altitude, distance, the driver camera and further overlays on or off individually.

Tap an overlay in the video to select it; drag it to move it and pinch to resize it. Tap an empty spot to clear the selection. For the selected overlay, the bar below the video shows − and + for the size; tap the percentage to type an exact value. Design opens appearance, colour and background. The arrows next to it undo or redo every change.

In portrait (9:16), Larger preview hides the tiles to give the video more room; Choose elements shows them again. Under Adjust you can also move overlays in small steps, make all of them compact or reset positions, so dragging and multi-finger gestures are optional. With Snap to guides, overlays align to the centre and margins while dragging.

Overlays stay inside the video and may overlap. The arrangement applies to the whole clip and its export; portrait and landscape keep separate positions. Done saves the layout for this ride; Cancel asks before discarding changes. Original recordings and measurement data stay unchanged; missing values appear as a dash.

In Video Studio, open the layout editor, tap an overlay and then Design in the bar below. Adjust > Overlay > Appearance opens the same choices. Speed offers digital, dial and bar designs; G-force offers a circle, a short motion trail or two axes. Acceleration / braking is an additional optional overlay with a bar or trace. Altitude, route, time and delta have suitable alternatives.

Choose a design, accent, background and size. Apply changes the draft; Done in the layout editor saves the complete look. Undo and redo include design changes. Personal presets and separate video archives retain the design.

The preview loops a short section of your recorded data. Reduce Motion or VoiceOver keeps it still. In the movie, displays always follow video time. Missing data is never invented. Speed is GPS speed, not RPM; acceleration is not pedal position. The G-circle shows felt load, while the axes show positive acceleration and left turns. Scale limits never change numeric values. Delta retains fixed comparison colours. Measurements and original videos stay unchanged.

Tap the question mark at the top right. The introduction highlights controls one by one and explains what they do. Next and Back move between steps; Skip introduction closes it at any time. Each video screen offers its introduction on first use. Afterwards, it appears only when you tap the question mark.

Long explanations scroll. Large text and VoiceOver are supported. Highlighted controls cannot be activated accidentally during the explanation. Tutorials never start recordings or change measurements or purchases, and restore expanded sections and the previous scroll position afterwards. No introduction opens during an active measurement recording.

Use the measurement screen’s recording button; in lap mode select a valid course first, then tap Prepare recording. Choose Start without video for measurement only, or Set up video for measurement with video. Sprint shows a PRO label for this option; lap and distance timing already require the Full Version. Select resolution, optional driver camera and sound. The preview does not record anything yet. Start measurement + video and the storage confirmation then start both together in portrait or landscape. The orientation at Start stays fixed for this recording, including after interruptions. Stopping ends measurement and video. Use Back to change the recording type; Cancel starts nothing. Video covers the entire drive and every lap, not just the fastest. Siri, Shortcuts and Apple Watch start measurement only, without a camera. In Settings > Video, turn off Enable video recording to start sprint, distance and lap measurement directly without the video prompt. This preference is saved. Existing videos and ongoing recordings are unchanged; turning it back on restores the choice at the next start. Race Video requires currently verified Full Version access; a legacy cached unlock alone is not sufficient. Before starting, the app checks free storage and shows an approximate recording duration for the selected resolution, driver camera and sound. The estimate deducts a 2 GB reserve, adds 25% to the expected data rate and allows extra time to close files. Below 30 minutes it warns; below 2 minutes beyond the reserve, or if the check fails, video cannot start. Space is checked again when starting and periodically during capture. Video stops near the reserve; telemetry remains independent. Other apps can consume space, and battery or heat can end recording earlier. This is not a duration guarantee or reserved disk allocation. Export and Photos copies need additional space. Also choose the frame rate (30, 60 or 120 fps, depending on the iPhone) and Standard or Ultra Wide if available. Unsupported resolutions are disabled. A dedicated status shows video elapsed time and interruptions. Video time starts with the first accepted frame.

Yes. Open the ride’s Video Studio from History. Under Choose your clip you find Entire drive, the best recorded lap, single laps or a range from the first to the last chosen lap, and sprint clips. Sprint clips show this ride’s saved best times; targets from the same run, such as 0–50 and 0–100 km/h, form one clip with up to 3 seconds before and after. Choose time range sets a free range with thumbnails and 0.1-second steps.

The status shows complete, partial or missing video. An export creates a new file without trimming or deleting the other laps. The export bar estimates file size and space needed, including the copy and reserve. A finished export can be saved or shared again. Original videos are stored in Track4Facts and are not part of the JSON app backup; separately restorable video archives are under Settings > Backup & Export > Video backup. Restore the matching measurement data first.

Secure the iPhone in portrait or landscape and keep the app open and screen unlocked. Automatic screen locking is disabled while the camera is ready or recording. Locking or leaving the app pauses video and creates a gap. If the same measurement recording is still running, video resumes automatically in a new section when the app is active again and the camera is available. Heat, low storage or camera errors can stop video permanently; telemetry is independent. Completed video segments remain available, but a hard interruption can lose the last segment. Front/rear combinations and 4K depend on the device. Unsupported choices are rejected, not silently relabelled. Portrait export preserves the full road frame. Speed and position use GPS estimates. The G-circle prefers suitable stored motion data and falls back to GPS estimates when sensor data is missing or unsuitable; missing data is not invented. An optional heart-rate overlay uses recorded Watch values. It is off by default and requires separate confirmation for each video export. Check people, sound and visible location before sharing. A new capture or export requires verified Pro access, including when using remote controls. Available devices and formats are checked in advance; actual camera resource costs can still prevent preparation.

Choose resolution and frame rate in camera setup. 30 fps is the default and needs the least storage. 60 fps looks smoother and makes frame steps and slow motion steadier. 120 fps is meant for slow motion: the export can show every frame at a quarter of the speed.

Which combinations are possible depends on the iPhone, lens, resolution and driver camera. Unavailable options are greyed out and name the reason, for example “only without the driver camera” or “at 1080p or lower”. The driver camera always records at 30 fps.

Like the Camera app, 4K at 120 fps is saved as HEVC (H.265), which needs about 30 % less data for the same picture quality. All other combinations use H.264 for the widest playback. More frames per second and higher resolution need more storage and produce more heat; the storage estimate before starting accounts for this. Record in 4K for the sharpest result; 1080p is often enough for social media.

Tap the video to show or hide the controls; during playback they disappear on their own after a few seconds. Play/pause and the 10-second jumps sit in the middle. A jump briefly pauses, moves to the exact frame and then plays on.

For rides with laps, the arrows next to the lap display jump to the start of the previous or next lap. The speed button cycles through 1×, ½× and ¼×. While paused, the arrows next to it step single frames back or forward.

Drag along the timeline to find a moment; a tap jumps straight there. Moving your finger up away from the bar while dragging makes the search four times finer. White marks are lap starts, and you feel a light tap when crossing one. After you let go, the video plays on if it was playing before. The button at the bottom right opens full screen.

The bar below the preview shows the whole ride. Orange is recorded video; hatched areas are video pauses, for example from switching apps, locking the iPhone or camera errors. The white frame marks the selected clip; even a sprint clip of a few seconds stays visible as a narrow frame. Tap the bar to choose a time range.

Very short gaps of a few frames (up to about a quarter of a second), which can occur when the video file is changed internally every few minutes, do not count as pauses: preview and export hold the previous frame there while the telemetry continues. Longer pauses stay hatched and show a note in the video with the reason, if known. Measurement data always stays on its original timeline.

The driver picture exists if you switched on the driver camera when recording. Whether that is possible depends on the iPhone; it cannot be added afterwards. In the layout editor, switch it on with the Driver camera tile, move it and resize it between 50 and 260 %: with two fingers, with − and + or by tapping the percentage.

It has rounded corners and a fine border like the other overlays and fills its area; edges that do not fit are cropped. The driver camera has no designs. It records at 30 fps. Check who is visible before sharing.

To keep playback and jumps smooth, the studio renders the preview with telemetry at the export resolution, but at most 1080p. The export uses the chosen resolution, up to the recording resolution. For the full sharpness of a 4K recording, choose 4K when exporting. The default is 1080p, which suits most platforms and creates smaller files.

In 9:16, a road view recorded in landscape only uses the portrait width and therefore looks smaller and less detailed. For portrait videos, record in portrait. At 480p, use fewer or larger overlays.

In Video Studio you choose the format (16:9 landscape or 9:16 portrait), the resolution up to the recording resolution and the frame rate. The summary shows resolution, frame rate, format, duration and the estimated file size. Exports are MP4 files.

The frame rate is limited to the recording’s; the default is 60 fps or less, which most players and platforms show. For recordings at 60 or 120 fps, Slow motion (Slow ½× or ¼×) shows every recorded frame at 30 fps: 60 fps becomes half speed, 120 fps a quarter. Slow motion is exported without sound, and the telemetry slows down to match. 4K at 120 fps is saved as HEVC.

After exporting, the share sheet opens directly; Save to Photos and Share / Files remain available afterwards. Original recordings and measurement data stay unchanged.

From iOS 26, the export continues when you leave the app or lock the iPhone, as long as iOS allows it at the time. Progress then appears in the system indicator; rendering takes considerably longer in the background. When it is finished, share or save it in Track4Facts. If you stop it in the system indicator or iOS pauses it, your recordings stay unchanged; just export again.

Before iOS 26, or if iOS declines the background export, keep the app open while exporting. The note shown during the export tells you which case applies.

The original road and driver camera recordings are stored in Track4Facts, not in the Photos app. Rides with video carry a Video badge in History. Exports are separate copies in Photos or Files and remain when you delete the originals.

In Video Studio, “…” → Delete video only… removes all camera recordings of this ride; the measurement data stays. This cannot be undone. Under Settings > Video > Video storage you see every ride with its recording date and the storage it uses. Tap a ride for Save all…, Save road camera… and Save driver camera… (without a driver camera Save video…): the app records in 5-minute parts and joins them into one file per camera without re-encoding or quality loss; pauses between parts are left out. This briefly needs about as much free storage as the video’s size. If there is not enough, you can save the individual 5-minute parts instead. The files go through the share sheet, for example to Files, Photos or AirDrop, named with date and camera. You can also delete videos there. Create and restore separate video archives under Settings > Backup & Export > Video backup. The regular JSON app backup contains no videos.

Yes. The G-circle and Acceleration / braking overlay prefer suitable stored iPhone motion data. New rides store it at a nominal 50 Hz, independently of GPS. The existing sensor analysis estimates vehicle axes and timing alignment using GPS data, removes gravity and checks calibration. The iPhone must be firmly mounted and the ride must contain enough useful data.

Sensor identifies sensor analysis; GPS identifies fallback when motion data is missing or unsuitable. Source changes are not blended. Valid neighbouring values are interpolated at video time, never across data gaps. A higher video frame rate creates no additional measurements and no greater accuracy. Older rides can benefit if sufficient motion data was stored; missing data cannot be reconstructed.

Felt load in the G-circle remains: acceleration down, braking up, left turns right and right turns left. The graphic has a fixed ±2 g scale; acceleration is not pedal position. Manual telemetry offset applies to these overlays too. Preview, editor and export use the same prepared analysis. Raw data, saved results and sprint, distance and lap measurement remain unchanged.

First assign a garage vehicle to the ride in the app. Open Video Studio → Design telemetry and enable Vehicle card. Select it; Design offers four variants: Compact (name only), Name & text, Vehicle details and Photo card. Adjust colour, background, size and position; editor changes support undo. The card is off by default.

Edit caption accepts up to 80 characters, such as tyres or event. Without custom text, a summary of year, displacement and fuel is shown. Compact shows only the name. Details come from the vehicle profile, not measured engine performance. Missing values stay blank; missing photos receive a placeholder. The entire vehicle photo is fitted without cropping.

The card uses this ride’s assigned vehicle, not the currently active vehicle. Reopen the studio after profile edits. Presets retain the look but do not enable the card or copy its caption. Separate video archives contain no vehicle profile data or original vehicle photos: also restore your regular backup with vehicle assignments. Exported videos permanently include the visible card.

The plate field and private notes are not copied automatically. Photos and custom text may still reveal personal information; there is no automatic blurring. Inspect the preview before exporting and sharing.

If a call or alarm only takes the microphone, video continues without sound after a brief gap; sound returns automatically once the microphone is free. After a temporary interruption, such as switching apps, the existing video sections are finalized. If the same measurement recording is still running, the app is active again and the camera is available, video resumes automatically in a new section. The time in between is not recorded. Studio automatically combines all sections of the same ride; gaps show a notice and the reason when known. Measurement data stays on its original timeline. Storage problems, high system or thermal pressure, missing Full Version access and camera errors are not automatically bypassed. A stopped ride is never restarted. Automatic continuation is not guaranteed after the app is terminated.

In the layout editor (Custom), under Timing & comparison, explicitly choose a reference lap to enable ≈ Distance delta. − means faster and + slower than the reference at the same travelled distance, not necessarily the exact same track position. The reference lap itself shows no delta.

Only completed laps with near-complete boundary coverage, no detected gaps, standstill or discarded position samples are offered. Lap distances must agree within 3%; compared positions must be within 25 m and have similar headings. These checks do not guarantee accuracy. Unsuitable data shows — instead of an invented difference.

Telemetry offset opens a pausable preview. Positive values show later telemetry earlier; negative values show earlier telemetry. Adjust in 0.05-second steps within ±5 seconds or reset to original timing. Done saves the change for this ride; Cancel discards it. A non-zero correction is visibly labelled in the exported video. Cameras, sound, clip boundaries, originals, measurements and records do not change. Personal presets do not transfer offsets or reference laps to other rides; separate video archives preserve each ride's layout. Real driving tests remain necessary to assess recording synchronisation.

The optional Sector / time overlay uses only existing stored sector times from completed laps. It shows the current sector and elapsed time within it. It is off by default and can be added in the layout editor. If sectors are missing or their stored times do not match the lap, the value stays blank (—). No sector crossings are detected again and no records are changed. This overlay does not include a delta against a reference lap.

Best recorded lap selects the fastest completed lap with consistent stored timing. This is not a new measurement or additional quality certification. If video is missing, the studio shows partial or missing coverage instead of silently selecting a slower lap. All other laps and original videos are retained.

Choose time range shows a thumbnail timeline. Drag the orange handles to set the start and end. White marks indicate lap starts; hatched areas indicate missing video. Sliders and ± controls also let you adjust boundaries in 0.1-second steps without dragging.

In the layout editor, Snap to guides is optional. When enabled, dragged overlays align with the centre and matching edge margins. My presets stores up to 20 named combinations of overlays, positions, format and export quality. Presets work across rides; a driver camera that was not recorded stays off, and export resolution is limited to the original. Clip selection and measurement data are not transferred.

Export shows preparation, rendering and final validation. No unreliable remaining-time estimate is promised. The video card in ride details shows recorded video duration, file size and possible interruptions.

Yes, if pulse values were recorded for this ride using Apple Watch Race Training with Health permission. In Video Studio → Custom, enable Heart rate. Select the element and tap Design to choose Digital, Pulse ring or 30-second trend, then adjust colour, background, size and position. Missing recordings cannot be reconstructed. After Watch transfer, reopen Video Studio if the values are not available yet.

Values follow video time and the selected telemetry offset. The last measurement remains visible for at most 10 seconds with its age; gaps stay blank. The ring has a fixed 20–260 bpm scale, not training zones. The trend is not an ECG or medical assessment. Heart rate is off by default and is not enabled through personal presets.

Before each export with this overlay, you can explicitly include pulse, export without it, or cancel. This permission is separate from Health access and backup/CSV consent. Pulse becomes part of the video pixels, including shared or Photos/iCloud copies; later disabling cannot remove it from those copies. Original camera recordings and separate video archives receive no raw heart-rate samples. Restoring a video layout does not grant export permission.

Yes. In Video Studio → Custom there are separate Best sprint and Best distance time elements. Enable one or both, move them independently and choose a design, colour and size for each. Best sprint shows the speed range and its duration; Best distance time shows the distance target and the time needed for it. Distance is a different element for the total distance travelled.

A ride stores the best time per target, the same one you see in History. That is exactly what the cards show, from its recorded finish until the car stands still again for the next run; then “Ready for the next run” appears. Other attempts of the same ride are not shown and not recalculated from GPS data, so the video only shows measured times. Timing method and quality stay visible; results without an exact finish time are omitted.

Every telemetry element has a Compact design in addition to its existing looks. Select a placed element and tap Design → Compact → Apply. Compact is a purpose-built smaller layout, not just smaller type: narrow number strips, a mini route and G-circle, and separate small best sprint and best distance cards. Timing method, quality, units, estimates and pulse age remain visible. Large charts and individual best-sector details are omitted from the compact lap board; the ideal time remains labelled as theoretical.

In the layout editor, Adjust → Make all overlays compact changes all currently enabled telemetry at once. Selection, colours, background and positions are retained within the canvas bounds. Driver-camera size is unchanged; resize it separately. Undo restores the previous looks in one step. Compact and large elements can be mixed, moved, resized and saved as presets. No new element is enabled automatically, especially not pulse, and pulse export still requires explicit permission.

At 480p, avoid too many overlays or use larger sizes: compactness cannot replace resolution. Check readability in the exported video.

Activate Siri on your iPhone and, with Siri set to English, say for example:

“Hey Siri, Sprint recording in Track4Facts PRO”
“Hey Siri, Lap timing recording in Track4Facts PRO”

“Start sprint in Track4Facts PRO” and “Start lap timing in Track4Facts PRO” are also registered phrases. With German Siri, the recording phrases are “Hey Siri, Sprint-Aufnahme in Track4Facts PRO” and “Hey Siri, Rundenzeiten-Aufnahme in Track4Facts PRO”.

Each command toggles its mode: if nothing is recording, it starts. If that same mode is already recording, it stops and saves without asking for a name, provided data was recorded. To stop, say the same recording phrase again. If the other mode is running, its recording is left untouched.

A generic “Stop” is not a Track4Facts command and Siri may interpret it as ending a Watch workout, for example. If Siri does not recognise the app name, create a shortcut with a distinctive name and say that name instead. Set up and start before driving; voice control must not distract you either.

Open Track4Facts once after installing or updating it and finish the introduction and safety notice. Then open Apple's Shortcuts app, create a shortcut with + and search the actions for Track4Facts.

Choose “Start or Stop Sprint” or “Start or Stop Lap Timing”. For example, add only “Start or Stop Sprint” and name the shortcut “My sprint recording”. You can now tap it or say “Hey Siri, My sprint recording”. You do not need an extra “Open App” action.

The shortcut toggles between starting and stopping; even a shortcut you name “Start” stops an already running recording of the same mode. Lap timing requires the Full Version and a previously selected course or valid start/finish line. A shortcut does not bypass permissions or any unlocking required to start.

On an iPhone with an Action Button, open Settings → Action Button, select Shortcut and then choose a shortcut. Select the Track4Facts entry “Sprint” or “Lap Timing”, or a shortcut you created earlier.

For example, create “My sprint recording” with the “Start or Stop Sprint” action as described above and assign it to the Action Button. Press and hold the Action Button before driving: Sprint recording starts. Pressing and holding it again runs the same shortcut and stops and saves the running Sprint recording. This is a toggle, not separate start and stop buttons.

A locked iPhone may need to be unlocked to start. Stopping a running recording can happen in the background. The Action Button does not replace location permission; the volume buttons are not used as recording buttons.

Open Track4Facts once, complete the introduction and safety notice, and allow location access. Close any open dialogs. Lap timing requires the Full Version and a selected course or valid start/finish line; Sprint works without the Full Version.

To start, the app moves to the foreground if needed so GPS can activate. A locked iPhone may request Face ID, Touch ID or its passcode. Start recording before driving. A running recording of the same mode can be stopped and saved without opening the app; for voice control, iOS must allow Siri while locked.

If the entry is missing from Shortcuts or the Action Button picker, open the updated app once and search for Track4Facts again. For voice issues, check that Siri is enabled and your phrase matches Siri's language. Use your own shortcut name if needed. Check the start confirmation and recording indicator before driving off.

Start recording while stationary and wait for “Ready”. You do not need to drive first, and the stop counter does not have to show 1. It counts a later detected transition from motion to standstill and is independent of sprint readiness.

A 0–X measurement is a state machine with Waiting, Ready, Running and Result phases. It reaches Ready only after a confirmed stationary sequence within the 3 km/h tolerance. A displayed 0 km/h alone is not sufficient: a current speed fix reliable enough for the active GPS source must also be available. If “Waiting for standstill” remains visible despite 0 km/h, open GPS diagnostics. For iPhone, inspect sample age, horizontal accuracy, speed and speed accuracy; for XGPS or Dragy, also inspect source, 2D/3D fix and continuity. Individual XGPS accuracy values that are not supplied may legitimately show “–”.

On transition from the last stationary point to the first valid moving sample, the 3 km/h crossing is linearly interpolated. This t₀ is the computational start anchor, while the user-facing start remains zero. The target crossing time is estimated in the same way. Their difference is the sprint time, and the fastest valid attempt for each range is retained within the ride.

This describes the GPS time. Accepted sensor fusion instead uses its motion-based estimate of launch and target crossing. GPS and fusion therefore use different start anchors.

The app compares GPS speed with the iPhone's motion data: acceleration, gravity direction and rotation. Timestamps show which readings belong to the same moment.

The iPhone must remain firmly mounted during the ride. The app estimates the car's forward direction from motion data and checks whether that trace agrees with GPS. It accounts for GPS readings that may be delayed or briefly unchanged.

If the two data streams do not agree well enough, or the iPhone moves in its mount, no regular sensor-fusion time is shown.

Regular iPhone sensor fusion is intended for 0–100 km/h and 0–60 mph using internal iPhone GPS. It needs two GPS fixes after the target fix and motion data through that point. The live display waits up to about 3.5 seconds when necessary, showing “…”. If confirmations are missing or no stable model fits, the GPS time remains primary. A final check follows when recording stops.

GPS and motion sensors must agree. Missing standstill evidence, larger gaps, phone movement or unstable delay estimation may prevent regular fusion. The estimate may be longer or shorter than GPS; the smaller number does not determine acceptance.

History can reprocess older recordings with suitable raw data. Fusion from the withdrawn method no longer counts as confirmed: without successful recalculation, the original GPS time is shown again. Raw data are retained. This iPhone fusion is not used for custom speed ranges, distance times or external GPS receivers.

During a ride, the app saves a compact, time-stamped series from the iPhone motion sensors: device acceleration and, where available, acceleration without gravity, gravity direction and rotation rate. For eligible iPhone sprints, GPS samples for sensor fusion are also saved with the ride. These can support a finer speed trace. Otherwise, sprint comparison uses the saved GPS speed points.

Older rides may lack these additional series. A saved sprint time alone does not contain a complete speed trace. Even newer rides may lack samples at launch or before the target, or have gaps that prevent comparison. What matters is the data actually stored for that ride, not just the displayed app version.

Internal acceptance checks data quality and model stability. It does not guarantee that fusion is closer to the true time than GPS for every ride. The examined comparison rides were used during development and are not an independent accuracy validation.

GPS can report the start and finish with different delays. Its time can therefore be too short or too long. An accepted fusion can likewise be shorter or longer. It takes priority because its checks passed, not because its number is smaller or because of a vehicle reference time.

Fusion is also a model estimate. Sensor drift, GPS smoothing, road grade, phone movement and an uncertain standstill can affect it. Stored sensitivity values are not guaranteed error bounds; no fixed sprint timing accuracy has been established.

An X–Y range does not require complete standstill. It only arms after the active ride has observed a valid speed below X. This prevents a recording started above X from producing a false 50–100 result.

Timing starts when X is crossed and ends at Y. Both times are interpolated between valid GPS samples. Slowing below X later rearms the range for another attempt.

Open the range settings at the top right of the Sprint page. You can add start and target speeds, remove values and reorder the list. Start must be lower than target; duplicates and implausible ranges are rejected.

In the Full Version, every range in the list is measured on each new ride. Up to three selected ranges appear live on Sprint in list order. Without the Full Version, only 0–100 km/h or 0–60 mph is measured, depending on the selected unit; additional saved ranges remain intact and return after unlocking. Changes apply to the next ride and never alter an active or historical recording.

A range can be completed several times during one ride. Track4Facts retains the fastest valid time for each range; a slower later attempt does not replace it.

When the ride ends, every range configured for that ride is stored, including ranges whose target was never reached. This preserves what was intended to be measured.

A receiver produces discrete pairs (t₁, v₁) and (t₂, v₂). If threshold v* lies between v₁ and v₂, Track4Facts uses a linear model within that short interval: t* = t₁ + (v* − v₁) / (v₂ − v₁) × (t₂ − t₁). Using t₂ unconditionally would make threshold times late depending on sampling phase.

Interpolation assumes that speed changes approximately linearly and monotonically between neighbouring, already validated samples. It reduces sampling error but removes neither GPS noise, receiver latency nor model error during strongly nonlinear acceleration. Large or invalid time gaps are therefore not treated as ordinary intervals.

For exact endpoint values and a twice-differentiable speed curve, the value error of linear interpolation is bounded by Δt²/8 · max|v̈|. Turning that into a timing bound also requires a non-zero slope at the crossing; approximately, the value error is divided by acceleration. Errors in the two GPS speed values contribute separately. The formula is therefore a model estimate, not a guaranteed total accuracy for the sprint time.

Common reasons include an insufficiently supported standstill for 0–X, a rolling range that did not first pass below X, target not reached, an interrupted attempt, insufficient GPS quality, a sampling gap or an implausible speed jump.

History → ride → Acceleration times shows the ranges selected for that ride, their regular times, quality or stored failure reason. With suitable iPhone raw data, an orange estimate may also appear. It explains a possible trace but does not turn a rejected attempt into a confirmed measurement.

History and acceleration details prefer accepted sensor fusion. Otherwise, an available estimate appears with ≈ and the Estimate label; if neither exists, GPS is displayed. Tap ⓘ for the original GPS comparison value.

This presentation does not change stored measurements or confirmed records. An estimate remains a reconstruction without guaranteed accuracy.

Sprint comparison overlays saved traces for 0–100 km/h or 0–60 mph. Both start at 0 seconds. Time since the start runs horizontally, speed vertically. The open drive is solid; the selected comparison drive is dashed. Tap the chart to read both speeds at the same elapsed time.

The total difference compares saved sprint times. It does not tell you which car led at a particular place: the drives may have used different roads.

Use “Choose comparison” to select another drive and optionally filter one or more vehicles. “Best matching drive” searches that selection for the shortest saved sprint time with a usable curve. It excludes the open drive and requires the same speed range, source (GPS or sensor fusion) and regular/conditional classification.

You can also choose a drive directly. Different sources trigger a notice; that comparison is only indicative.

A saved time alone is not enough for a chart. GPS curves also require saved start and finish timestamps and matching samples between them. Missing raw data, large gaps or a mismatched model trace may therefore prevent a curve even when the time appears in history.

Comparison does not create new records. Weather, slope, tires, load and phone mounting are not normalized. Sparse GPS points remain coarse; a finer fusion curve does not prove greater accuracy.

Each curve belongs to its drive’s saved sprint result. GPS uses the corresponding speed samples; sensor fusion uses a matching model trace with the same start, finish and duration. Blue indicates regular fusion, orange conditional estimates or GPS curves. Read the source label and any estimate label.

A missing fusion curve is not replaced by an independently calculated GPS curve. An older model trace may only be reconstructed if it matches the saved result. Intermediate fusion speeds are model estimates, not individually validated measurements.

Without regular fusion, this comparison uses the stored GPS time whenever it exists, even if History highlights an additional ≈ estimate. Only without a regular time may the conditional model trace be used. GPS starts at the interpolated 3 km/h crossing; fusion and estimates use their modelled launch. Aligning both at 0 seconds therefore does not establish an identical physical start.

Distance timing requires the Full Version and arms automatically after confirmed standstill. As with a 0–X measurement, the computational start anchor is the interpolated crossing of the 3 km/h tolerance, while the user-facing start is still shown as standing. A launch is confirmed only when speed reaches at least 5 km/h within three seconds after the 3 km/h crossing. Evaluation then starts retrospectively at the interpolated anchor. A recording begun in motion therefore obtains a comparable distance attempt only after the next confirmed standstill.

For every valid interval, distance is numerically integrated from speed using the trapezoidal rule: Δs = (v₁ + v₂) / 2 · Δt, with v in m/s (km/h ÷ 3.6). This is the area under the speed-time curve with speed assumed to change linearly. If a target lies within an interval, a remainder d is still missing there. With a = (v₂ − v₁) / Δt, d = v₁ · τ + ½ · a · τ²; the app solves this in the numerically stable form τ = 2d / (v₁ + √(v₁² + 2ad)) and obtains the finish timestamp t₁ + τ and finish speed v₁ + a · τ. This means 100 m or 400 m need not coincide exactly with a GPS timestamp. Returning to standstill before the target interrupts the active attempt.

All distances enabled in Distance settings are measured in parallel, regardless of the row currently selected. Selection only controls which target is shown in the large card with time, finish speed and progress.

Enabled distances beyond the selected target remain part of the ride. Timing finishes when the largest active distance is reached or the attempt is interrupted.

After each newly confirmed standstill another attempt can start automatically. For every enabled distance Track4Facts retains the fastest valid time within the active ride. Finish speed, exact clock time and GPS quality are stored with that best result.

Stopping recording writes the complete set of reached and unreached distances to the ride as a snapshot.

Open distance settings at the top right of Distance. Switches decide which split and target distances are measured in parallel on the next ride. Tap an active distance to select it for the large target card.

Under Manage custom distances you can add names and lengths. Input follows the unit chosen in general Settings and is stored safely in metres. Changes during an active recording do not alter its frozen configuration.

A time over distance is only comparable when its start is unambiguous. If ride recording begins in motion, normal trip data continues, but distance timing waits for the next confirmed standstill. It then shows Ready and starts automatically at launch.

The large card shows the fastest time for the selected target, speed at the finish and current attempt status. While driving, the bar fills according to integrated distance.

The list below shows all active split and target distances. Once reached, best time and finish speed appear; a dash means that distance has not yet been reached validly during this ride.

No. For distances such as 100 m and 400 m, the app integrates valid speed samples from the active GPS source over time. It interpolates the start and the instant at which the selected distance is reached. The iPhone fusion for 0–100 km/h and 0–60 mph does not change these distance times.

Distance timing requires a confirmed standstill. A reading just over 3 km/h is treated only as a possible launch. The attempt is confirmed if speed reaches at least 5 km/h within three seconds, then replayed from the interpolated 3 km/h crossing. Slow creeping alone does not start a valid distance attempt. Missing or widely spaced samples can interrupt it.

The complete lap/racing mode is part of the Full Version. After unlocking, you can capture a course with your own survey lap, draw its shape, or use “Import a file” to load GPX or GeoJSON track data. A .json file must contain GeoJSON. Check the shape and driving direction, place start/finish and any sectors, and save the course with a name. Only crossings in the chosen start/finish direction count.

You can select saved courses again and edit their shape, start/finish and sectors. The following FAQ entries explain importing, editing and usage rights.

The first valid crossing of the start/finish line starts timing. It is not yet a completed lap. Every following valid crossing in the configured direction finishes the current lap and immediately starts the next one.

A crossing counts as a completed lap only after at least ten seconds have passed since the last timing anchor, at least 30 metres have been covered, the vehicle has moved at least 15 metres away from start/finish, and enough confirmed movement samples exist. If a crossing does not meet these conditions, no lap is saved, but it may become the new provisional timing anchor. GPS gaps longer than five seconds are not bridged, preventing a position jump from inventing a lap.

Sectors divide a saved course into sections. Place sector lines on the recorded course; the app automatically aligns each line across the direction of travel. The lines must be crossed in their configured order. The final sector runs from the last sector line back to start/finish.

While driving, the cards wrap onto additional rows whenever one row is too narrow. Green marks a new or matching sector best; red indicates time lost.

The large number is the running lap time. You also see current speed, lap count, active sector, best and last lap, and the most recently completed laps.

Once a reference lap exists, the delta compares your current time at the same distance travelled since the lap started with the best lap so far. A negative green delta means faster; a positive red delta means slower. Portrait and landscape rearrange the sector cards for the available space.

The live delta matches the distance travelled since the lap started, rather than an exact geographic position. Different racing lines and GPS errors can shift that correspondence.

A lap receives a complete sector set only when every sector line was detected in the intended order. If a line is missed because the car deviated from the course, the line is too narrow, GPS accuracy is limited or there is a sampling gap, Track4Facts keeps the valid lap time but deliberately stores no partial sector sequence.

Check the route and gate width in the course editor. Wider gates can help with variable GPS, but should not cut across a neighbouring part of the course.

Above the list are the best lap, the theoretical best assembled from the quickest sectors, and consistency as the spread of the lap times; tapping a lap opens its comparison with the best one.

The fastest completed lap is highlighted in green. Every other lap's delta shows its deficit to that best time. Its sectors appear underneath as individual cards.

The quickest recorded time for each sector is green – it may come from a different lap than the overall best lap. A sector delta compares that card with the quickest time for that particular sector. If no complete set exists, the lap explicitly reports incomplete sector data.

"Theoretical" is the sum of the quickest time recorded for each individual sector of the session, regardless of which lap it came from. It is therefore not a lap that was driven but a lower bound assembled from parts already demonstrated: every sector was covered that quickly, just not in the same lap. The line under the card names the lap each best sector came from, which can be checked against the green sector tiles.

It appears only when at least two laps carry complete sector sets. A lap that missed a sector line carries no sector times at all, so it neither contributes nor blocks.

"Consistency" is the sample standard deviation of the session's lap times, given as a plus-minus figure in seconds. It describes spread, not level: two drivers with the same best lap differ here when one hit it once by chance and the other repeated it.

In formulas, with tᵢⱼ the time of sector i in lap j: T_theo = Σᵢ minⱼ tᵢⱼ. Consistency is s = √(Σⱼ (Tⱼ − T̄)² / (n − 1)) over the n lap times Tⱼ with mean T̄; the denominator n − 1 (Bessel's correction) accounts for T̄ itself being estimated from the same laps. If lap times are roughly normally distributed, about two thirds of the laps lie within ±s of the mean.

Two laps are plotted against distance covered rather than time. This approximately aligns the same parts of the course; different driving lines and GPS variation can shift that alignment. Both charts are pinned to the same span and label width so that the same distance covered sits at the same position in each.

The time difference at a point is the elapsed time of the compared lap minus the interpolated elapsed time of the reference lap at the same distance. Live display and later review use the same interpolation rule. Recording gaps, filtering and later reconstruction can still produce differences.

Formally: Δt(s) = t_B(s) − t_A(s), where t_A(s) is interpolated linearly between the two reference points with s_k ≤ s ≤ s_k+1. Because time grows over distance as dt/ds = 1/v, the slope of the difference curve is d(Δt)/ds = 1/v_B − 1/v_A. Where the curve rises, the compared lap is slower at that point; a flat section means equal speed, even if the deficit remains.

The worst-stretch hint measures over a sliding 100 m window. Measuring only between neighbouring samples would produce a metre-and-a-half window at 25 Hz and tend to find noise rather than meaningful sections; fixed tiles could split a relevant area at a tile boundary.

Nothing extra is recorded for this: every lap carries its start and end time and every waypoint a timestamp. Laps are reconstructed from those values. Older sessions can also be compared when their stored points and timestamps are sufficient.

A corner is not read from a track layout the app does not know, but from what the driver did: a drop in speed of at least 12 km/h that comes back up. The trace is first resampled onto a five-metre grid and smoothed over 25 metres, so the windows mean the same at 10 Hz and at 25 Hz. Corners are matched approximately between laps by distance from the start line.

"Slowing starts" is deliberately not called a braking point. What is measured is where the smoothed speed first falls 2 km/h below the straight before it. Lifting off, aerodynamic and rolling resistance, engine braking or regeneration, and travelling uphill can slow the car without the brake pedal. Smoothing and receiver latency also shift the detected onset by several metres. Processing both traces identically improves comparability, but does not guarantee that systematic effects from different driving lines, reception or receiver latency cancel completely.

Only meaningful differences are listed, largest first. Differences under five metres and under 1 km/h are omitted because they typically lie within the uncertainty of a GPS trace.

How much time a speed difference costs follows from the same relation dt/ds = 1/v: if a constant Δv is missing over a distance L, the loss is approximately Δt ≈ L · Δv / v². Example: 3 km/h less at 100 km/h, held over 200 m, costs about 0.22 s. A slower corner exit before a long straight can therefore weigh more than the same difference before the next corner.

Standstill can also occur on a closed circuit. Long waits can dominate the comparison of the actual driving. Forty seconds at a light is not a driving mistake, and an analysis that charges it to the nearest corner is worse than none.

A standstill is fundamentally invisible in speed plotted against distance: standing still produces time but no distance, and on a distance axis it is a single point. It is therefore read out of the elapsed times. Corners and the worst-stretch search skip anywhere either lap stood still.

The header splits the gap - "36.9 s, of which 32.5 s standing, 4.4 s driving" - and a toggle takes the waiting out of the delta curve as well. It appears only when a lap actually stood still. The split can reverse the sign: a lap can be slower overall and quicker on the move than the best one, when that one simply had a shorter red light.

The default is 40 m. In the Tracks tab each gate can be set between 10 and 200 m, and the map draws sector gates at their actual width with ticks at both ends.

A pass counts when the straight connection between two consecutive valid GPS points intersects the gate in the direction of travel. Time is interpolated at the intersection: t = t₁ + λ · (t₂ − t₁). A large along-track sample spacing does not automatically prevent a straight valid segment from intersecting. A curved path between samples, a rejected gap, direction error or lateral position error can still miss a gate. As a starting point, gate width can be road width plus twice the currently displayed horizontal accuracy: an 8 m road and a 2 m diagnostic value give 12 m; a 5 m value gives 18 m. These are examples, not fixed accuracies for a device class.

A gate that is too narrow raises the risk of missing a lap or sector. A very wide gate can intersect a neighbouring entry or exit at a tight location. There, adapt its width as closely as possible to the road and current reception quality.

Ghost Lap replays at least two complete, usable laps from the same recording. Select your lap in the title at the top. In “Fastest lap” mode, the ghost is the fastest usable lap in that recording.

Both markers show the same elapsed time since the lap start on a shared track line. The orange marker is the ghost. Red highlights on the track indicate sections where time is lost to the ghost. This shared line makes timing easier to compare; it does not display two independently measured racing lines or a centimeter-accurate physical gap.

The time difference compares your lap with the ghost at the same track progress. Plus means your lap takes longer; minus means it is faster. The top value is the total lap-time difference; the chart and current value show how it develops around the lap. For difference values and sector bars, red indicates time loss and green a lead. The chart shows track progress horizontally and the difference in seconds vertically. A rising trace means an increasing deficit; a flat trace means a constant difference.

Progress is based on traveled distance. Matching sector timings align the sector boundaries. Stops at the same progress are accounted for: additional standing time creates a deficit, while GPS jitter should not move the marker forward.

The ideal lap combines the fastest usable sectors from this recording. It requires at least two matching laps with complete sector timings. Its total is the sum of those best sectors; the source lap may change at a sector boundary.

This assembled lap was not actually driven. Speed and racing line may not match at a source change. The ideal lap shows a theoretical opportunity, not a guaranteed achievable lap time.

Existing lap times and GPS points are used. Laps missing start or finish data or containing detected recording gaps are excluded. GPS errors, differing path lengths and spatial alignment limit the precision of the comparison.

The track line is cleaned to reduce stationary position jitter. Below 4 km/h, very slow rolling may be treated as stationary. The spatial display is therefore a processed replay path. This does not change saved lap times.

Play and pause control the replay. The slider seeks to a time; 1×, 2× and 4× only change playback speed. “Sector details” opens the saved sector timings. Tap a sector to jump to its start in your lap.

Without matching sectors, comparison against the fastest lap may still work. The ideal lap and sector list may then be unavailable for some selections.

Switch to racing mode and open “Tracks”. Choose “Import a file” there or through the plus button, read the usage notice and tap “Choose file”.

Supported inputs are GPX tracks and routes, and GeoJSON geometries containing track lines or polygon exterior rings. A .json file must contain GeoJSON; arbitrary JSON files, Track4Facts backups and CSV files are not track imports. Files are limited to 25 MB. A directly imported circuit must be closed or have its first and last points no more than 40 metres apart; very short or invalid geometries are rejected.

Track4Facts can detect repeated laps in a longer GPX recording, including recordings with a lead-in and lead-out. This will not work for every recording. If several laps or layouts are detected, compare their map lines and lengths and choose a suitable one. The import brings in the course shape, not a complete recorded drive with measurements.

Next, check the line, adjust the detail using “Points on the line”, and correct points and driving direction as needed. Place start/finish and any sectors, then save the course. Imported data is checked technically, but neither its accuracy nor its usage rights are verified.

Images, photos and PDF track maps cannot be imported.

Use your own GPS recordings or track data whose rights holder or licence permits the intended use. GeoJSON, GPX and JSON are interchange formats; the format and a free download do not grant permission to use the content.

Third-party track data may be subject to copyright, database rights and provider terms. Coordinates derived from maps or satellite imagery can also fall under these restrictions. Use such data only with appropriate permission. Displaying a map background in the app does not grant permission to copy its content or build a track database from it.

Follow the relevant licence: OpenStreetMap data, for example, is licensed under the ODbL; public use or redistribution may require attribution and compliance with additional licence terms. Keep records of the source and licence. Import does not automatically preserve all licence and attribution information; you must include required notices yourself when sharing. If rights are unclear, use your own GPS recording or obtain permission.

Track4Facts processes the selected file on the device and does not upload it to a Track4Facts server during import. Map display does use Apple services. Saved courses may be included in an app backup you export or in enabled Apple system backups. Local processing does not remove licence obligations. The import feature does not provide a third-party track catalogue, and Track4Facts does not verify rights or licences for selected content.

In the import editor, “Points on the line” controls how much detail is retained. Drag a point to move it, tap the line to add one and tap a point to remove it. After manual edits, the detail slider locks so it cannot overwrite your corrections; Undo can unlock it again. “Reverse driving direction” reverses an imported course.

Use the tools menu to redraw a section between two selected endpoints or the entire shape. For a saved course, open its actions and choose to edit its shape. Small corrections retain timing gates where possible. Larger shifts or direction changes may require start/finish or sectors to be placed again; Undo restores the previous state.

Map and satellite views help with orientation. Respect the usage rights of source material and check the shape, driving direction and timing gates before the next recording.

The chart is inspired by the friction circle and shows the vehicle’s longitudinal and lateral acceleration. Every dot is one moment of the drive; distance from the origin is √(a_x² + a_y²), the combined planar acceleration. A cross means strong longitudinal and lateral acceleration occurred mostly separately; filled diagonals mean they occurred together more often.

The classic friction circle is a simplified model of combined longitudinal and lateral tyre force. A real force boundary is often closer to an ellipse and varies with factors including longitudinal and lateral slip, wheel load, tyre condition and road surface. Track4Facts does not measure those quantities. The cloud alone therefore cannot determine the friction coefficient, the share of available grip used or a possible time gain. The combination percentage in the app only describes how often |a_long| and |a_lat| both reached at least 0.10 g among moments with at least 0.15 g combined acceleration.

From the GPS track alone. Longitudinal acceleration is the time derivative of speed. Lateral acceleration follows from path curvature: three distinct, non-collinear positions determine a circle. Its radius r follows from the side lengths and triangle area (r = abc / 4A); together with speed v it gives centripetal acceleration v²/r. The sign of the cross product separates left- and right-hand corners.

Three conditions bound the method. The points must be at least six metres apart, so the time window is widened at low speed. Nothing is computed across a recording gap. Because sustained cornering keeps the same sign while position noise often changes sign, the series is median-filtered over a window.

In formulas: a_long = (v₂ − v₁) / Δt and a_lat = v² / r, each divided by g = 9.80665 m/s². If r is estimated 10% too small, lateral acceleration comes out 11% too high. Position noise therefore distorts a short arc more than a long one.

From Core Motion on the iPhone. New drives capture device acceleration and, where available on the iPhone, gravity direction and rotation rate. Track4Facts requests 100 Hz; the rate the device really delivers is calculated from sensor timestamps. New rides average incoming values in 20 ms windows and save them at a nominal 50 Hz, regardless of GPS provider or measurement mode. The actual rate depends on the sensor samples delivered. This reduces high-frequency vibration and uses far less storage than the full stream, but it is not a calibrated reference measurement for individual impact peaks.

The car's longitudinal axis is estimated rather than assuming a phone orientation. In the horizontal plane it is the direction whose sensor acceleration agrees with the smoothed time derivative of GPS speed. Smoothing adapts to the actual GPS rate: repeated iPhone speed values, genuine 10 Hz data and a 25 Hz receiver are treated differently. The app also searches for up to 1.5 seconds of timing offset between motion and GPS. The relationship must meet a minimum strength and the drive must contain enough real acceleration or deceleration; a merely plausible chance fit is not enough.

For older recordings containing only total acceleration, gravity is still reconstructed per segment from the long-term average. A segment that fails the gravity, density, excitation or agreement checks is discarded; if too few segments remain, the sensor view is deliberately not shown.

New rides save a compact sensor series at a nominal 50 Hz, regardless of the g threshold, GPS provider or measurement mode. Older rides may have a lower rate. Only older drives still depend on the storage threshold used at the time; below about three readings per second there is not enough density for a measured curve.

The sensor view is also omitted if phone orientation is not stable enough within a segment or the gravity and axis checks cannot support reliable projection. For old data without a separately stored gravity vector, an unsuitable mean estimate can also cause a segment to be discarded; that result alone does not prove one specific cause.

Too little usable acceleration or an incomplete GPS speed series can also prevent reliable estimation of forward direction and timing offset. If fewer than six segments in ten produce a plausible axis, the app shows only “Derived” instead of an uncertain sensor fit.

The two views use different input signals: “Derived” obtains acceleration from GPS speed and path, while “Measured” projects iPhone sensor data onto estimated vehicle axes. They are not fully independent because the sensor analysis uses smoothed GPS speed change to estimate the longitudinal axis and a possible timing offset. The comparison is a plausibility check, not an independent reference measurement.

The displayed percentages are Pearson correlations between time-paired readings. They describe how similarly the two series rise and fall; they are not a percentage equality of the numerical values. The series run at different rates and use different filters, so their percentiles are not the same quantity either.

A difference is not automatically an error and has no predetermined direction. Projection and calibration, road banking, phone orientation, GPS reception, time alignment and filters can affect the series differently. Large differences increase uncertainty and should be read together with the quality indicator.

Corner dynamics shows how fast the car rotates about its vertical axis – the yaw rate in degrees per second – and compares it with the lateral acceleration from the GPS track. In steady cornering without drift, ψ̇ = v / r and a_lat = v · ψ̇ = v² / r (ψ̇ in rad/s; times 180/π gives °/s). Example: 100 km/h is 27.8 m/s; on a 95 m radius that gives ψ̇ = 0.29 rad/s ≈ 16.8 °/s and a_lat = 8.1 m/s² ≈ 0.83 g.

The large number at the top is the 95th percentile of yaw rate, so it reflects a typical strong corner rather than a single outlier. “Left rotation” and “Right rotation” are determined separately. The second view shows roll and pitch rate: how fast the body leans to the side or dips forward. Tap the question mark at the top right for the detailed explanation with diagrams.

The iPhone’s MEMS gyroscope measures rotation rates about the phone’s three axes. Track4Facts projects rotation vector ω onto gravity direction ĝ: yaw rate = ω · ĝ. This obtains the component about Earth vertical regardless of how the firmly mounted iPhone is oriented. On a graded or banked road, Earth vertical does not fully coincide with the vehicle’s vertical axis, so yaw, roll and pitch components can project differently. Without road-orientation data there is no universal correction using a single tilt angle.

For roll and pitch the app also needs to know where “forward” is inside the phone. It learns that direction by matching sensor acceleration with GPS longitudinal or lateral acceleration. The iPhone must therefore stay firmly mounted for the whole drive. A soft or vibrating mount particularly increases uncertainty in roll and pitch rate.

The percentage is Pearson’s correlation coefficient for yaw rate and GPS lateral acceleration across moments with at least 0.03 g of lateral acceleration. It describes how similarly both quantities rise and fall; it is not a percentage equality of their values. For planar cornering without significant sideslip, a_lat ≈ v · ψ̇. Because speed also enters the relationship, correlation can remain below 100% even with good data when slow and fast corners are mixed.

“Good” appears when there are at least 10 sensor readings per second, the vehicle axis is reliably calibrated, gravity direction does not jump by more than 20° within half a second, correlation is at least 35% where it can be calculated, and the GPS series has no relevant gaps. If any condition is missing, the rating is “Limited”. That means higher uncertainty; the figures can then deviate more from the actual motion.

Corner dynamics needs stored rotation rates from the motion sensor. If a drive contains no such data or the recording is too short for it, a note appears instead of the analysis.

Roll and pitch rate are missing when the vehicle's forward axis could not be calibrated reliably – for example with too little accelerating and braking, weak GPS reception, or a phone that changed position. Yaw rate remains available in that case. The analysis does not determine understeer or oversteer, because that would require steering angle.

Background: whether a car understeers or oversteers is described by the understeer gradient K. In the linear single-track (bicycle) model, steady-state cornering follows δ = L / r + K · a_lat, with road-wheel steer angle δ and wheelbase L (T. D. Gillespie: Fundamentals of Vehicle Dynamics, SAE 1992; test procedure ISO 4138). Yaw rate and lateral acceleration provide r and a_lat – but without a measured steer angle, K remains undetermined.

Strictly speaking it measures deceleration, how strongly the car slows down: a = −Δv / Δt, expressed in g with 1 g = 9.81 m/s². “Braking” is the common and easily understood word, which is why the analysis carries that name. Pedal position or brake pressure would require vehicle telemetry.

Besides the brakes, aerodynamic and rolling resistance, engine braking or regeneration, and an uphill gradient can contribute to measured deceleration. Drag is F = ½ · ρ · c_d · A · v²; with ρ = 1.2 kg/m³, c_d · A = 0.7 m² and a mass of 1,500 kg it corresponds to about 0.02 g at 100 km/h and 0.09 g at 200 km/h. Uphill, a gradient of p percent increases deceleration by approximately p/100 · g, so 5% contributes 0.05 g; downhill it acts in the opposite direction. The 0.15 g threshold marks a clear deceleration phase but does not prove that the brake pedal was pressed. Tap the question mark at the top right of the braking analysis for the detailed explanation with diagrams.

A phase starts at 0.15 g of deceleration and has to last at least 0.2 seconds. Short dips below the threshold of less than 0.3 seconds do not end it, missing readings for more than half a second split it, and phases less than 40 m apart are merged. The values preferably come from the motion sensor of the firmly mounted iPhone. For a single drive without usable sensor data, the app derives deceleration from GPS speed.

For context, a phase can be approximated with constant deceleration a: s = (v₀² − v₁²) / (2a) and t = (v₀ − v₁) / a. From 100 to 40 km/h, constant 0.4 g would give about 83 m and 4.2 s; 0.8 g would give about 41 m and 2.1 s. Real deceleration is usually not constant, so these examples show scale rather than an exact reconstruction.

On the map, grey means no notable deceleration below 0.04 g, or no sensor data. Up to 0.15 g the colour turns yellow, up to 0.30 g orange and up to 0.45 g red; above that it stays red. How corners are compared between two laps is described in the question about corner analysis.

The ribbon follows the recorded GPS track. Its height comes exclusively from the GPS elevation profile, never from speed. The colour shows longitudinal acceleration: yellow to red for decelerating, grey for an almost steady speed between −0.04 and +0.04 g, turquoise to mint for accelerating. Dark grey means no reading was within reach at that point.

Formally the model is a space curve: the position (x, y) is the GPS position projected onto a flat map, the height z is the GPS elevation times the exaggeration factor, and the colour encodes longitudinal acceleration a_x in g. This puts location, elevation profile and accelerating or decelerating into one view.

The marker plays the drive back in real time or at 5× or 10× and shows speed and longitudinal acceleration at that moment. Drag to rotate, pinch to zoom, and use View to switch between perspective and top view. In lap sessions the analysis first shows the best lap. The width of the ribbon is a display width, not the width of the road. Tap the question mark at the top right for the detailed explanation.

The ribbon ends at real recording gaps instead of drawing an invented connection. A gap is Δt > max(1 s, 4 · Δt_typ), where Δt_typ is the median sample spacing of this recording – above 4 s at 1 Hz and above 1 s at 25 Hz. An ordinary stop does not split the ribbon. Points below 4 km/h are omitted so stationary position noise does not form a knot.

A few metres of height would barely show next to a long route. For a flat profile, the app therefore exaggerates height in whole steps up to 6× and states the factor in the subtitle. Below 2 m of elevation range, the model stays flat. GNSS altitude is often less stable than horizontal position because of satellite geometry, but the ratio depends on receiver, constellation and surroundings and has no fixed factor. At 6× exaggeration, a 5% gradient appears as 30%.

Intensity (RMS) summarizes movement over about half a second. Peak is the largest filtered excursion within that window. A short jolt can therefore stand out even when intensity is low. A passage is marked when RMS reaches 0.08 g or peak reaches 0.20 g. These are display thresholds, not safety or road-quality limits.

The top average and peak summarize usable windows without clear braking or acceleration. The map, chart and individual locations also show these maneuvers, so they may show a higher peak than the summary. Coverage describes usable windows as a share of assignable driving time, not confidence in pothole detection.

Teal shows lower, orange medium and red higher measured movement. For sensor gaps up to 2.5 s, the map blends between the neighboring colors; the chart and metrics do not gain invented readings. For longer gaps or stops, a light gray section follows GPS only. GPS outages remain open. The chart shows RMS in orange and peak as a dashed blue line. Tap the route, a marker or the chart to inspect measured values.

The route stays solid even during clear braking or acceleration. Those measurements remain visible but are excluded from the summary metrics. Tap a point to see the speed change. Purple markers indicate pronounced cornering when the GPS path and phone rotation agree. Both are only possible influences on movement, not proof of its cause.

A movement may come from uneven pavement, vehicle motion or a loose phone. Potholes, curbs and their depth cannot be reliably identified. Stationary periods, longer GPS or sensor gaps and strong phone tilting are excluded. Normal cornering does not interrupt the measurement. Compare drives only at similar speeds and preferably with the phone firmly mounted.

The iPhone measures its own vertical movement. The app uses the direction of gravity so a fixed portrait or landscape mount can work. Slow changes in orientation and very fast interference are attenuated. The signal describes movement at the phone, not directly at the road surface.

The Watch app can start and stop a normal ride recording on the paired iPhone. When you stop, the iPhone saves the ride without a naming dialog; you can rename it later in History.

The Watch does not currently start a configured lap-timing session. Course, start/finish and sectors are selected and started from Lap timing on the iPhone.

Before starting, the Watch shows the latest saved ride with distance, duration and top speed. While recording, speed, duration, top speed and distance take priority. A newly completed sprint from the live ranges selected on the iPhone appears as a large result card for a few seconds. When Race Training is enabled, current heart rate appears too.

After stopping, the Watch confirms that the ride was saved and shows distance, duration, top speed, average speed, completed sprint times and—when measured—average and maximum heart rate. On iPhone, History shows the heart-rate curve and, for a lap race, average and maximum heart rate per lap.

No. For position, speed and the actual ride recording, the iPhone remains the measurement and storage source. The Watch receives those values from the iPhone and sends start/stop commands, so it follows the iPhone's unit and speedometer scale. The GPS source is either the iPhone itself or—with the Full Version and already connected before the ride starts—an XGPS150, XGPS160 or Dragy Lite on the iPhone. The Watch does not pair directly with the receiver.

When Race Training is enabled and Health access is granted, the Watch additionally measures heart rate itself and saves the workout to Apple Health.

The Watch shows “No iPhone” while there is no direct connection. A start or stop command can be queued and delivered when the iPhone becomes reachable again. Until the iPhone confirms it, do not assume recording has already started or ended.

Location permission and storage remain on the iPhone. If location is disabled there, the Watch cannot start a recording.

Race Training is optional and off by default. When enabled in Settings, the Watch starts a genuine workout alongside a normal ride recording, keeps the live view active and records your pulse. It can read heart rate and save the workout to Apple Health only after you grant Health access. Because Apple does not offer a motorsport workout type, Health lists it as an “Other” workout with the name Track4Facts Race Training. If the ride is discarded, no workout is saved either.

Timestamps align pulse values with the matching Track4Facts ride and, during a lap race, with each lap. The values stay local in the app and are excluded from exports by default. They are included in future backups and waypoint CSV files only after your separate explicit consent under Settings → Backup & Export. GPX and motion CSV always remain heart-rate free. In Video Studio, pulse can be added as an optional overlay; each video export requires its own confirmation, independent of backup/CSV consent. Ride recording and the Watch remote remain fully usable without enabling it or granting Health access; there is simply no heart-rate recording and watchOS may leave the app after its usual interval. A workout uses noticeably more Watch battery.

During an active recording, the Live Activity shows recording duration, current speed, distance and top speed. It automatically follows the unit selected on the iPhone and ends with the recording.

Live Activities must be allowed for Track4Facts in iOS. If a ride is started from Apple Watch while Track4Facts is not in the foreground, iOS may initially refuse the Live Activity; opening the iPhone app adds it to the already active ride.

Enable “Announce results” in Settings. Underneath it, each kind can be switched on its own - top speed, acceleration times and lap times - and “Play a sample” speaks one example sentence for every kind that is enabled, in the current voice, without needing a drive. In lap mode, Track4Facts speaks every valid lap time, followed by whether it is the first or a new best, whether it matched the best, or how many seconds it was behind. Each lap is compared with the best time that had already been set before it.

In sprint mode, new top speeds and best times for the up to three selected acceleration ranges are still announced. Other audio is only ducked while the message is spoken. Voice and pronunciation come from iOS. A high-quality voice downloaded under Settings → Accessibility → Spoken Content will usually sound more natural.

Garage lets you create vehicles with a photo, technical specifications, colour and registration plate. One complete vehicle entry is free; additional vehicles require the Full Version. Existing or backup-restored vehicles remain visible. New recordings are assigned to the active vehicle; you can change the choice before starting. Existing rides can later be assigned to another vehicle or no vehicle.

A vehicle page combines its rides, total distance, drive time, top speed, and acceleration and distance bests. Deleting a vehicle never deletes its rides; it only removes their assignment.

Acceleration results with sensor fusion, sprint comparison, Ghost Lap, vibration analysis, friction circle, corner dynamics, braking analysis and 3D analysis have a question mark at the top right. It opens a dedicated scrolling explanation with diagrams: what is analyzed, how to read it, what data is needed and where the limits are. The FAQ also summarize these topics.

Under Settings → Feedback you will find “Rate the app” and “Send feedback by email”. “Rate the app” opens the review page in the App Store directly. “Send feedback by email” opens a draft to support@track4facts.com containing the app version, iOS version and device model; nothing is sent until you tap Send yourself. If no mail app is set up, the address is copied.

Stored data includes start and end, route, valid GPS samples, speed, distance, top speed, stops and elevation values. Where available during recording, time-stamped acceleration and motion data from the iPhone sensors are stored with the ride too. Sprint and distance snapshots add the ride's ranges, results, quality and failure reasons. A lap-timing ride also stores completed laps and any available sector times.

All canonical values remain metric in the database. History converts them to the currently selected unit when displayed.

Tap a ride in History. The map, naming, Race Summary and acceleration times remain directly accessible. Speed, altitude and acceleration charts, Replay, lap and sector times, lap comparison, distance times and GPX, waypoint CSV and motion CSV exports require the Full Version. The action sheet offers analyses according to the data available for that ride.

At ride start, Track4Facts creates an immutable snapshot of the semantically relevant configuration: sprint ranges, order and selection of live values, and active target and split distances. On completion, results, quality grades and failure states are stored on the ride together with that configuration.

This snapshot principle versions the measurement definition. Later global setting changes cannot retroactively alter the semantics of historical data. Units are separate: canonical values remain metric in storage and are converted only for the current presentation.

Older rides remain readable. Existing legacy sprint values for 0–30, 0–50 and 0–100 are adapted to the new results view; unreached values stay visible as dashes.

An old ride without a distance snapshot cannot gain reliable distance times after the fact because its targets and splits were not stored. The app explicitly explains this instead of inventing values.

Telemetry replay follows the stored GPS samples along the map over time and synchronises speed and available sprint information. Marker heading is derived from a stable direction towards subsequent points. At standstill or between nearly identical points, the last plausible heading is kept so the marker does not spin erratically.

Tap a ride and choose Name ride to assign a useful title. Full Version raw-data exports are in the same action sheet. In portrait, swipe a History row to the left to delete it.

Deletion permanently removes the ride and its related GPS and motion data from the app. You can first export a complete Track4Facts backup from Settings with the Full Version; importing an existing backup always remains available.

Open a ride in History or Garage. The 4:5 Race Summary image and shareable vehicle card are directly available. Raw GPX, waypoint CSV and motion CSV export requires the Full Version and is only useful when the corresponding data exists.

Heart-rate data is excluded by default. If, after the warning, you explicitly enable “Heart rate in backup & waypoint CSV” under Settings → Backup & Export, waypoint CSV files from History and Garage receive matching time-aligned heart-rate values. GPX and motion CSV remain heart-rate free. Export files are not uploaded automatically; only the sharing action you initiate passes the selected file to the app, person or service you choose. Map requests, Watch communication and Apple system services such as device backup or Health synchronisation are separate processes.

Under Settings you can save all rides including GPS and motion data, lap results, Garage, saved lap-course layouts with the current selection, and supported app settings in one .track4facts file. Heart-rate data is excluded by default and is included in future backups only after your separate explicit consent. That consent itself is neither backed up nor restored on another device. On import, included heart-rate values are stored locally with the ride; existing rides are recognised and skipped. Older backup formats remain readable.

Backup export is included with the Full Version, while an existing backup can always be imported.