The majority of the are earned by competing in events and meeting specific criteria:

Most standard cars are unlocked by reaching specific levels. You earn fans by performing stylish moves, hitting opponents with power-ups, and completing "Fan Runs" during races.

If the game crashes on startup, use Task Manager to set the process affinity to CPU 0 , then re-enable all processors once the game is running.

Another method to unlock all cars is by editing the game's configuration files. This method requires some technical expertise, but it's a safer option than using cheat codes.