Extra Car Colors: When customizing a car, select Change Color from the list of options. At the Change Color screen, press Up, Right, Down, Left, Triangle, Circle, X, Square. If you have entered the code correctly, more color options will appear at the color bar at the bottom of the screen.
Unlock Everything: At the main menu, press Square, Square, Up, Right, Down, Left, L2, R2, L1, R1. If you entered the code correctly, a menu will appear that allows you to unlock all cheats.