After you select a car, there will be a password option. Enter spaces by pressing Right. You may enter more than one password.

Code		Effect
STX_O		Invincibility
T_SOO		Infinite weapons
OOTX_		Overhead Camera
STOSS		Secret Level
OTSOO		Warehouse District
XSSOT		Freeway Free For All
XTSOS		River Park Rumble
XSTTT		Cyburbia
STXOX		Rooftop Combat
TXOST		Minion!
STOSS		Fight For Your Life

Horn Code:

When the computer is selecting the opponent cars, press and hold L1, Circle, Square, Up, Left on the D-pad through the whole loading stage. A horn will be replaced with your machine guns that will move any car out of your way.