Activate the following cheats by completing different levels in Career mode with an "A" rank. The more "A" ranks you have, the more cheats will be unlocked. Select "Options" at the main menu. Then, select the "Cheats" option to toggle the cheats. Enabling cheats will disable high scores and rewards:

CHEAT CODE - CHEAT FUNCTION
Big Wheels - Big wheels and propellers.
Invincibility - Become invincible.
Iron Man (13 "A" ranks) - Half health.
Laser Law - All police weapons shoot blue lasers, others shoot red lasers.
Law Lord - Full Justice at all times.
Open Road - No civilian traffic.
Reoffender - Double the loss on all negative justice.
Speed - Increases your speed.
Sticky Feet - Cannot be thrown out of vehicles.
Wild Water - Water is always choppy.