S.C.A.R.S.

Enable all codes
Enter "WLLVDD"
or
Go to the character selection screen and press
Left, Up, Right, Down, Z, R, Down, Left, Up, Right

Enter the following codes:

Cheetah car: Enter "NRNNRR"
Cobra car: Enter "TRTTLL"
Panther car: Enter "4MSTTR" or "YMSTTR"
Scorpion car: Enter "SDSSRT"
Unlock Crystal Cup in Grand Prix mode: Enter "LGSSSX"
Unlock Diamond Cup in Grand Prix mode: Enter "CRKKYY"
Unlock Zenith Cup in Grand Prix mode: Enter "DZPKKK"
Master mode and all bonus cars: Enter "PXPRTS"
All cars and cups: Enter "GGWWOO"