The following codes only work on vehicle levels:

Frantic mode - pause the game, hold L and press X, Y, B, Y, X, release L.
Berserk mode - pause the game, hold L and press X, Y, Y, X, Y, B, release L.
Trailers mode - pause the game, hold L and press X, B, B, X, release L.
Double armor - pause the game, hold L and press B, Y, X, B, B, release L.
Triple armor - pause the game, hold L and press B, Y, X, B, B, B, release L.
Quadruple armor - pause the game, hold L and press B, Y, X, B, B, B, B, release L.
Super bullets - pause the game, hold L and press B, B, B, B, release L.
Faster game mode - pause the game, hold L and press X, Y, B, WHITE, X, Y, B, WHITE, release L.

The following codes only work on Enemies Vanquished.

Drive Shelby Cobra - pause the game, hold L and press RIGHT, RIGHT, LEFT, LEFT, UP, release L.
Drive SUV - pause the game, hold L and press X, B, Y, X, Y, release L.
Bonus Alpine Race - pause the game, hold L and press B, B, X, X, Y, release L.