How to Run a 0-100 Acceleration Test That Actually Means Something

An acceleration test is the one measurement where a phone is genuinely competitive with a dedicated instrument, provided you understand what it is measuring and control everything else. The app times the run from a start speed you choose to a stop speed you choose, and files the result in its own Speed Test History. What determines whether that number is worth anything is entirely procedure.

What ruins a result

Gradient. A 1 percent downhill slope is invisible to the eye and worth a noticeable chunk of a 0-100 time. Test both directions on the same stretch and average them, or you are measuring the road rather than the car.

Surface and temperature. Cold tyres on cold tarmac spin where warm tyres grip. The first run of a session is almost always the slowest, and the difference is larger than most people expect.

Wind. A headwind costs time, a tailwind flatters you, and neither is obvious from the driver's seat. Again: run both directions.

Wheelspin. Excess wheelspin destroys the time. If the wheels are spinning, they are not accelerating the car.

GPS quality. A run started under a bridge or beside a tall wall begins with a poor fix. Get a clean sky view before the run, not during it.

A procedure that repeats

1. Pick a venue. A closed course or a track. On a public road, only where the speeds involved are legal and the conditions are genuinely safe.
2. Warm everything. Drive for ten minutes. Cold fluids and cold tyres are the two largest sources of run-to-run variation.
3. Mount the phone properly. Windscreen or dashboard, clear view of the sky, screen awake. A phone sliding around the footwell is not measuring your car.
4. Set the range before you move. In the app, choose the starting speed and the stop speed, then start the test while stationary.
5. Run it three times in each direction. Six runs total, with a cooling gap between them.
6. Discard the first run and take the average of the rest. The first is a warm-up whatever you tell yourself.

Reading the number

Compare like with like. Your figure is directly comparable to your own previous figures on the same road in similar conditions, and that is exactly what makes it useful: it tells you whether a change — new tyres, a different fuel, a service, a heavier load — did anything measurable.

It is not directly comparable to a manufacturer's published figure. Those come from ideal conditions and sometimes from a measurement convention that excludes the first fraction of a second of movement. A one to two second gap between your result and the brochure is normal and says nothing bad about your car.

What the app stores

Every run goes into Speed Test History as its own entry, separate from ordinary trips, so a testing session does not clutter your trip log. Ordinary trips are recorded separately with distance, total time, moving duration, stop time, average and maximum speed, and the route drawn on a map.

One last thing, and it matters more than any number: a test is not a reason to exceed a limit. If the venue does not allow the speed legally and safely, lower the stop speed. A 0-60 run on a road where 60 is legal tells you nearly as much as 0-100 does.