All Driving Upgrades:
Left, Right, Left, Right, A

All Fighting Moves:
Up, Down, Up, Down, A

All Gunplay Skills:
Right, Left, Right, Left, A

Bigger Car:
Down, Down, Down, A

Show Nick's Coordinates:
A, X, B, Y

Impound Garage Cars:
Up, Right, Down, Left, Up, A.

Play as Snoop Dogg:
While you are the city map screen, press R, Dpad Up, Dpad Right, Dpad Left, Dpad Down, Z, Z, A, Y, X, Y. You must make sure you go to a location and save the game before you exit to the main menu or it will not work.

License Plate Codes:
Enter the following as your license plate, then hold down L + R when you select OK to activate:

M1K3      Play as commando 
HAWG      Play as biker 
TFAN      Play as gangster 
B00B      Play as female punk 
JASS      Play as donkey 
TATS      Play as tatooed lady 
PHAM      Play as butcher 
MNKY      Play as male punk 
BRUZ      Play as boxer 
J1MM      Play as corpse 
FATT      Play as police officer 
P1MP      Play as pimp 
MRFU      Play as asian 
5WAT      Play as S.W.A.T. 
B00Z      Play as street bum 
PIMP      Play as pimp 
B1G1      Play as your boss 
ROSA      Play as your partner 
HARA      Play as asian worker 
FUZZ      Play as Officer Johnson 
HURT_M3   Play as your partner in underwear