All Circuits:
Highlight Africa on the map screen, then press R1, R2, R1, L1, Square, L1.

Performance Cars:
To unlock all performance cars, unlock the UK racing track. Then highlight UK on the map screen & press R1, Square, L1, Circle, R2, Circle.

GTI Cars:
To unlock all GTI cars, unlock the Rome racing track. Then highlight UK on the map screen & press L1, Circle, R1, Square, L2, Square.

Remote Control Cars:
To unlock the scaled-down radio controlled cars, unlock the USA racing track. Then highlight USA on the map screen & press Square, L1, R2, L2, Circle, R1. When you have chosen your vehicle & options, you must then hold Left + L2 on the white loading screen.