Test Drive II: The Duel Cheats

While racing on controller 1 hit A on controller 2 for a quick boost of speed

Start a new game, pick your car, and start a race. Before the cars start to move, hold the L and R buttons on Controller 2 to make the Customize Car Screen to appear. You can use Controller 2 to change your cars options. If you have enough speed, you can press the A button on Controller 2 to jump.