Hint: Honk:
Click the right thumbstick, you can barely hear it but it works.

Code for various cars & tracks:
Make a profile and put in WheelToWheel to get cars & Tracks

Code for Classic Cars:
Make a profile and put in TheGoodStuff

Code for Downhill Tracks:
Make a profile and put in Geronimo

Code for Endurance races:
Make a profile and put in TheLongHaul

Code for Unlimited Bonuses:
Make a profile and put in NoHoldingBack or NoHoldsBarred

Starting cars:
You start the game with these and earn others by gaining points as described below
Mitsubishi Lancer EVO VI
Subaru Impreza WRX
Ford Focus Cosworth
Peugeot 206
Ford Escort Cosworth Rally
Volkswagen Beetle

Mission tips:
Always shoot hinges or locks instead of blowing them because it is quieter. Always crouch behind objects and make sure that your squad is with you shooting or you will easily die. Shoot through car windows, as they are a useful shield.

Unlockables:
You can purchase these at the Special Features section.
ART Part I: Purchase for 10 Intel Points
ART Part II: Purchase for 10 Intel Points
ART Part III: Purchase for 10 Intel Points
ART Part IV: Purchase for 10 Intel Points
Increased Force: Purchase for 650 Intel Points
Invisibility: Purchase for 900 Intel Points
Once Shot Kill: Purchase for 600 Intel Points

Easy multi-player levels:
In multi-player P.E.C. mode there are two very easy
medals to get, 100 Kills and 100 Deaths. It is possible to go
from level 1 to 8 in about an hour just from getting these two
medals.

Invincibility Code:
While playing, press UP, UP, DOWN, DOWN, LEFT, RIGHT, LEFT, RIGHT, B, A. You will be invincible. Enter this code again to deactivate the cheat. Laser Trail Code:
During gameplay, press UP, DOWN, UP, DOWN, R-CLICK, R-CLICK. Your weapons will shoot blue laser trails, and enemy weapons will shoot red laser trails.

Hall of Fame:
At the main menu press: Left Thumb Stick, Left Thumb Stick, Right Thumb Stick, Right Thumb Stick, X, Y, B, A, B, A

No Cheat for you