Enter these as your name..
BEEFY................Unlocks the monster truck
LOWRIDER.............Unlocks the stock car
SPRINTER.............Unlocks the buggy
FIFTY................Unlocks the hot rod
FRIENDLY.............Unlocks track 7
SANDDUNE.............Unlocks track 8
CRAZY................Unlocks track 9
ELITE................Unlocks track 10
SNOWMAN..............Unlocks track 11
ALLTRACK.............Unlocks track 12
DAVON................Unlocks no collisions