Unlock all cars
To get all cars, hold L1,L2 and press Up (x6), Down (x11), O, X (x2) and start. You now will hear a horn to confirm the code.

Bonus After Tournament
Be sure you end 1st in a tournament to receive more game options, entries of new galleries, cars and film sequences.

Action Replay/Xplorer Codes
$B79F78383535 $17D21836C134 - All Cars
$B7A178383535 $17FE0842C134 - All Stages
$87CC46900134 - Full FMV Sequence
$871B236B2449 - Bonnet View
$876BAB7F10ED - Chase View
$77217A94D124 $87F0F29C179D - Turbo Boost (Press Up)
$77613AD49124 $872852EA3539 - Auto pilot (Press X and Up)

Ford Mustang Cobra SVT prizes
In Tournament mode, choose the Ford Mustang Cobra SVT and do all heats and you'll get:

Heat 1: Ford Ranger
Heat 2: Ballon Buster mode (multiplayer)
Heat 3: Volkswagon Microbus T2 1971