Turbo start:
Hold X when the yellow light comes on.

Top speed:
Hold down the reverse button while accelerating.

First Go to the Goodies screen. Each code requires 4 key combos.
Press and hold the following Combos together, pressing select while holding
the keys to enter into each game. After each entry a character will appear in
the bottom right hand corner of the screen.

Extra Characters:
L1, L1+L2+R2, L1, R1+R2

Additional Tracks:
L1, R1, L1+R1, L1

Tank Combat:
L1+R1, L1, L1, R1+R2

Submarine X:
L1+R1, R1+R2, L1+R1, L2

Motor Toon R:
L1, L1+R2, R1+R2, R1