Need for Speed: Porsche Unleashed
I have tested this glitch with all cars, and it only works with the Moby Dick car. Select manual transmission. Once in a race, simply leave it in first gear and hold the A button, you will continue accelerating at a constant rate. The fastest I've gotten the car up to with this glitch is 618 km/h. It also works in reverse.
Contributed By: ShenRyu.