Kurt's Spy Car
Enter Square(3), Triange, Circle, X.
All tracks
At the Press Start screen, press R2, L2, Circle, Circle, Square, Square.
All cars
At the Press Start screen, press R2, L2, Square, Square, Circle, Circle.
Smash Mouth car
At the Press Start screen, press Square, Square, Square, Triangle, Circle, X.
Unlock Bonus vehicles
Enter SMASHMOUTH as a code.