Grooverider Slot Car Thunder Cheats (GameCube)

Eagle: Win dining room on 3 volts

Spirt: Win dining room on 3 volts

Harrier: Win dining room on 3 volts

Bedroom: Win dinning room two times on 3 volts

If you go to championship and when you see an arrow on the track to
  skip the arrow and go right through it you can just hold the A, R,and
  L button you will go right through it. It's really cool you should try
  it you can also put tape on all of those buttons and you can just race
  the whole dang race with out hitting any arrows it's really cool.
  

Go to the main menu and choose "Single Player", then select "Time Trial." Enter BGM,
return back to the main menu to see the new option, CHEATS. It's under Special Features.

If you hold in A,R,L, and B you will just lift off the
  ground

  

Go to the main menu and choose "Single Player", then select "Time Trial." Enter MARK,
return back to the main menu to see the new option, CHEATS. It's under Special Features.