Think you're quick? Think you can drive? Prove it with g-tac. g-tac is the first car performance meter app to use both accelerometer and GPS for the most accurate results. Features:

- 0 to 60mph (100km/h) time
- 0 to 100mph (160km/h) time
- Quarter mile (400m) time and trap speed
- 60mph (100km/h) to 0 stopping distance
- 0-100mph-0 (0-160km/h-0) time
- Horsepower calculator
- G-meter for max accel/brake and lateral Gs
- Comparison graph of up to three stored runs
- Improved accuracy using GPS on iPhone 3G
- Typical accuracy of 1mph (1 to 2km/h)

Experiment and compare to see what launch techniques work best. And remember to drive that car like you stole it.