Take a very light vehicle you made using custom parts and do practice (you can do race, but it's hard to do). You can also use Kate Allen's car, Super Pirana. Set the engine settings fully to the left (for the most acceleration) and start. While riding around, go off a ledge and hold right and R or Left and L. Make sure that you aren't holding the control stick forward or back at all. You will start spinning in circles......backwards! And because the nose is a little down, you move up while going in circles instead of down. You can do this to skip from track to track and to reach crazy speeds (One player was able to reach 9,000 kph in a nosedive). A boost seems to slow you down when going these speeds.
Submitted by: CyberGlitch