At the main menu, enter one of the following codes:
All cars: ineedmorecars
All tracks: ineedmoremaps
Bonus track: fonekart
Faster race: speedracer
Low gravity: manonthemoon
High gravity: glued
Generate tracks: terraformers
Slippery track: greasy
Small wheels: gokartz
Large wheels: bigfootz
Big heads: bigheadz
Big hands and feet: boxerz