Cheat Mode
Go to the main menu and press Square, Square, Up, Right, Down, Left, L2, R2, L1, R1.
Furasshu Sama Car
Go to the car select screen and press Up, Up, Down, Down, Left, Right, Left, Right, Square, X. If you input the code correctly, the ultimate car, Furasshu-sama, will immediately appear on the screen. If your not fast enough you'll be taken to another screen upon pressing x.
Lights On Bottom Of Your Car
Go to Create Car Put In Up Down Left Right Up Down Left Right in 10 seconds fast. Lights Just Work At Night.
Get 300 MPH car
Go to the car select screen and press Circle, Square, L1, R2, Right, Left, Up.