During the course of the game in Career mode you will challenge the 5 Kings (Showdown, Drift, Drag, Speed and Grip), when you beat them you will unlock their car.

Unlock 1965 Pontiac GTO (Nate Denver):
In Career mode beat Speed King.

Unlock 1995 RX-7 (Aki Kimura):
In Career mode Beat Drift King.

Unlock 2006 Mustang GT (Karol Monroe):
In Career mode beat Drag King.

Unlock 2008 Evo X (Ryo Watanabe):
In Career mode beat Showdown King.

Unlock 2008 M3 E92 (Ray Krieger):
In Career mode beat Grip King.

These codes are input at the 'Enter Code' menu which can be found at the 'Career Mode' menu. It is advised that you disable the 'Auto-Save' option as some of these codes can only be used one time and you may decide you want to revert the game back to it's original setting.

Unlock Everything in the Game:
Enter the password 'UNLOCKALLTHINGS' to unlock ALL maps, cars etc.

Unlock ALL Bonuses:
Enter the password 'MASTERCODE' to unlock ALL the bonuses in Career mode.

Unlock Chevelle SS:
Enter the code 'HORSEPOWER' to unlock the Chevelle SS in Career mode.

Unlock Audi TT 3.8 Quattro:
Enter the code 'ITSABOUTYOU' to unlock the Audi TT 3.8 Quattro in Career mode.

Unlock Coke Zero Volkswagen Golf GTI:
Enter the code 'ZEROZEROZERO' to unlock the Coke Zero Volkswagen Golf GTI In Career mode.

Unlock Mitsubishi Lancer Evolution:
Enter the code 'MITSUBISHIGOFAR' to unlock the Mitsubishi Lancer Evolution in Career mode.

Unlock Energizer Lithium Dodge Viper SRT10:
Enter the code 'WORLDSLLONGESTLASTING' to unlock the Energizer Lithium Dodge Viper SRT10 in Career mode.

Unlock Castrol Syntec Decal:
Enter the code 'CASTROLSYNTEC' to unlock the Castrol Syntec decal in Vinyls.

Unlock Energizer Lithium Decal:
Enter the code 'ENERGIZERLITHIUM' to unlock the Energizer Lithium decal in Vinyls.

Unlock Extra $2,000:
Enter the code '1MA9X99' to get an extra $2,000 in Career mode (this password can only be used once).

Unlock Extra $4,000:
Enter the code 'W2iOLLO1' to get an extra $4,000 in Career mode (this password can only be used once).

Unlock Extra $8,000:
Enter the code 'L1iS97A1' to get an extra $8,000 in Career mode (this password can only be used once).

Unlock Extra $10,000:
Enter the code 'CASHMONEY', 'REGGAME' or '1Mi9K7E1' to get an extra $10,000 in Career mode (this password can only be used once).

Unlock 5 Free Repair Markers:
Enter the password 'SAFETYNET' to get 5 free repair markers in Career mode (this password can only be used once).