This is one of the few apps that does exactly what I want it to do... act like an automatic stopwatch-- while I concentrate on driving my car-- without having it hit "start/stop". My only suggestion for improvement, is that you can have a trigger time as low as 1mph, so it starts the moment the car lurches forward, and doesn't wait until 10mph. 1 second can go by then.

SpeedTimer 1.0
Start timer when your speed is greater or equal to goal speed.