Enter the car selection screen in race or trial mode. Highlight "Class A" and press L1 + Triangle. Quickly highlight "Class B" and press L1 + Triangle. Quickly highlight "Class C" and press L1 + R1 + Triangle. If you entered the code correctly, you will hear the sound of a squeal. Then, a new entry called "Special" will be available in the car selection screen. This new option allows the bus, Mack truck, Lamborghini, and scooter to be chosen.