Set a start/finish line, then drive. Your phone clocks each lap, tracks your best, and draws a live speed trace. Practice-day timing with zero hardware.
0
mph
0:00.0
this lap
—
best lap
GPS: not started
auto-lap offset a line to enable auto-laps
Reality check. Phone GPS updates about once a second and is accurate to a few meters — great for spotting which setup change helped and seeing your speed trace, but it isn't transponder-grade to the thousandth. Stand or mount with a clear view of the sky, set the start/finish line while sitting on it, and give it a lap to settle. Auto-lap fires when you re-cross within ~25 m of the line.