Use a memory card with a saved game from Burnout with free mode unlocked, or have that file on the hard drive. Begin Burnout 2 and load that game.
Beat Championship mode & earn gold medals in every race.
Win the Custom Series Championship.
Beat Grand Prix Championships Mode & get all of the gold medals in the challenges.
You must complete each of the following tasks to get new cars:
Classic 1970 Car: Destroy it with a police car in Pursuit 2.
Compact: Beat Custom Series Qualifier.
Coupe: Get all gold medals at Split Second Grand Prix.
Drivers' Ed Car: Get all gold medals in Driving 101.
Gangster Car: Beat Pursuit 3.
Hot Rod Car: Beat Face Off 1.
Japanese Car: Beat Face Off 2.
Muscle Car: Beat Pursuit 6.
Oval Racer: Beat it car in Face Off 2.
Pickup Truck: Beat Pursuit 5.
Police Car: Beat Pursuit 1 and destroy the boss's car.
Roadster: Get all gold medals at the Point Of Impact Grand Prix.
Sports Car: Get all gold medals at the Speed Streak Grand Prix.
Super Car: Beat Face Off 4.
SUV: Beat Pursuit 4.
Get gold medals in all of the challenges in Crash mode & beat Crash mode.
Unlock everything in the Custom Series Championship to get this option.
Win all Pursuit races in Championship mode to ulock Pursuit Mode.