Guides
How to measure acceleration, honestly.
Practical writing about timing cars with the phone you already own — including where a phone is genuinely not the right tool.
Reference
Trap speed, 60 ft, density altitude: what the numbers actually mean
A plain-English glossary of every number on an acceleration run — and the three that are actually worth chasing.
How-to
How to measure your 0-60 time accurately with a phone
Where you are allowed to do it, how to set the phone up, how many runs to take, and why your number will never match the brochure.
Buyer's guide
Do you need a performance box, or is your phone enough?
What dedicated hardware genuinely does better, why most phone timers deserve their reputation, and how to decide which one you actually need.
Free to start
GPS and accelerometer fused at 20 Hz, GPS readiness before you arm, and automatic rejection of runs the app cannot stand behind. No account.