Unlock the following cheats by collecting the corresponding amounts of hidden Rockstar Barrels. Note that enabling a cheat will stop your progress in Career mode and the earning of money and reputation in races:

CHEAT FUNCTION - BARRELS
Never Damage Out - 20 rockstar barrels
No Fines - 60 rockstar barrels
No Police - 50 rockstar barrels
Top Down View - 40 rockstar barrels
Unlimited Nitro - 10 rockstar barrels
Unlimited Special Abilities - 30 rockstar barrels