Type the code at main menu.

Code Effect

Down, Up, Left, Down, Right, Up, Square, Triangle Extra money
Left, Up, Left, Down, Left, Down, Right, Square. Infinite Nitrous
Down, Up, Up, Right, Left, Left, Right, Square Unlimited Crew Charge
Down, Right, Right, Left, Right, Up, Down, Square Unlimited Speedbreaker
Right, Up, Down, Up, Down, Left, Right, Square Unlock NFS:C Vinyl
Up, Up, Down, Down, Down, Down, Up, Square Unlocks Cardboard Box and Driver Vinyl

Unlock Bonus vinyl - To unlock burnout on the bonus section of vinyls you must have a burnout revenge save in the memory card you are using.

Unlock - burnout have a save game of burnout revenge

Unlock Collector Edition Cars - Successfully complete the indicated event(s) in the Challenge Series to unlock the corresponding car

Aston Martin DB9 (Exotic) Defeat Wolf in Boss Battle mode

Dodge Charger RT Classic (Muscle) Defeat the 21st Muscle Car Gang

Jaguar XK 2007 (Exotic) Successfully complete all three Turf War races

Mazda RX7 (Tuner) Defeat Kenji in Boss Battle mode

Nissan 240SX (Tuner) Successfully complete all three Checkpoint challenges

Unlocking crew members - You need a crew to help you out, but you have to do things to get their attention.

Colin Defeat Wolf

Neville (Blocker) Start of game
Nikki (Drafter) Beat all three "gangs"

Sal Complete 4-6 races
Sal (Scout) Complete 4-6 races
Sampson Defeat Angie

Yumi Defeat Kenji
Yumi (Scout) Beat Bushido