To change the color of your car, hold down the brake while shifting gears(either direction changes color once) in the car selection screen.
During the race, stop the car completely and hold down the brake, view change and gear up. The game will bring up a "yes and no" question. Choose yes and the game end. You can only do this once in each game. If you choose no and resume game, you cannot force quit anymore until the game is over.
Note: The force quit won't work if you have less than 8 seconds on the remaining time. This trick was tested on a single player mode.
This code can be entered in the Car Selection or Song Selection screens. All players must step on the Brake pedal and Shift up at the same time. The best way to make this work is just to get all players to hold the brake pedal and shift up and down constantly until a "No Handicap" box appears at the right.
Note: Shift up is gear up and it means to move the shift knob down. This trick also can be entered after real players mode is activate or vice versa.