Extra Tracks and Vehicles:
You need 2 controllers for this code...

Turn on the game and press Start on controller 1 until you see the screen that says "Push Start" (if you see "Grand Prix Mode", you're too far). On controller 2, press Up on the D-pad, C-Down, L, R, and Z all at the same time. Then release them. Immediately press Start or A on controller 1 to enter the Grand Prix mode. All tracks and cars should be available now.

Alternate Colors:
When choosing car, press R. Each car has 2 colors, except the controller, which has 4 colors.

Boost Start:
At the starting line, hold both the brake and the accelerator. When the starter says, "Go!", release the brake and your aerocar will rocket off the starting line.

Obtain Aeropad (flying controller):
Finish a race with the final 2 digits of your time being 64. This is really a matter of luck. Use this technique to get the other four hidden cars. NOTE: You must do it once for each car- you can't do it once and earn all the hidden cars