Hold L and press X, Square, Triangle, X, Triangle, Square at the main menu.

Press: X, Square, Circle, Circle, Circle, Triangle, Square, X at the main menu.

At the main menu click options, then cheats and enter the following:

While Holding L button. Square, Triangle, Circle, Square, Triangle, Circle

Different game unlockables:

Beat the goal time for one of the following tracks in Time Trial mode to unlock an alternate paint color for the indicated car. A different color will be unlocked depending on if you finish in first, second or third place.

The first shortcut is where there is about five or six obstacles. Jump or drive over them.