To access the cheat menu, hit all 4 C buttons, the Z button, and the 2 shift buttons while in the setup option. Now go into it and you should see various codes, but none of them are unlocked. The following are the combinations that will unlock the codes:

Mass: Hold L shift + R shift and press C-up, C-down, C-Left, C-Right

Killer Rats: Hold L shift + R shift and press Z(4)

New York Cabs: Press R shift, L shift, Z, C-UP, C-DOWN, C-UP

Resurrect in Place: Hold Z + C-LEFT and press C-RIGHT, then hold Z + C-RIGHT and press C-LEFT

Frame Scale: Hold Z + C-DOWN and press C-UP, then hold Z + C-UP and press C-DOWN

Tire Scaling- Hold Z + C-LEFT and press C-RIGHT, then hold Z + C-RIGHT and press C-LEFT

Auto-Abort: Press C-UP (4)

Burning Wreck: Hold C-UP and press Z (4)

Gravity: Hold Z and press C-LEFT, C-UP, C-RIGHT, C-DOWN. Do this 3 times.

Car Collisions: Hold L shift + R shift and press C-LEFT, C-UP, C-RIGHT, C-DOWN. Do this 3 times, then press Z.

Cone Mines: Hold Z and press both shift buttons (4)

Car Mines: Press Z + C-UP then C-RIGHT, C-DOWN, C-LEFT (6)

Track Orientation: Hold L shift and R shift and press C-UP, C-RIGHT, C-DOWN, C-LEFT (4)

Super Speed: Hold L shift and R shift and press C-UP, C-DOWN, C-LEFT, C-RIGHT.

Inside-Out Car: Hold C-RIGHT and C-DOWN and press L shift, R shift, Z, L shift, R shift, Z

Damage: Press R shift, C-DOWN, L shift

Invincible: Press L shift, C-UP, R shift (2)

Invisible Car: Hold L shift and R shift and press C-UP, C-DOWN (5)

Invisible Track: Hold L shift and R shift and press C-DOWN, C-UP (5)

Brakes: Hold C-UP and C-RIGHT and press Z 3 times.

Super Tires: Hold L shift and R shift and press C-UP, C-RIGHT, C-DOWN, C-LEFT (2)

Suicide Mode: Hold Z and press C-DOWN, C-LEFT, C-UP, C-RIGHT (2)

Do the Dew!: -Long code- Press L shift, R shift, C-DOWN, then L shift, R shift, C-LEFT, then L shift, R shift, C-DOWN, then L shift, R shift, C-RIGHT (2) then press Z

Levitation: Hold L shift and R shift and Z and press C-UP 4 times.

Fog Color: Hold Z and press all 4 C buttons down 4 times.

Game Timer: Hold Z and C-DOWN and press C-UP, then hold Z and C-UP and press C-DOWN.

Stunts: Hold all 4 C-BUTTONS and press R shift, A,Z,L shift.

If one of these does not work, and easy resort is to randomly begin hitting all of the buttons (except B) at once to unlock it.