Cheat Codes:
To use these codes you must be fast enough to have your time entered on the high score screen (make sure to turn checkpoints on in the Options screen). Make sure you have space on your memory card save this, and enter the following names for the desired effect -
knacked:        Reverse tracks
whoooosh:    Nitro when you press the horn
mjcim.rc:        Tiny cars
sausage:        Bonus cars

Drive the XPJ198:
Crazy as this sounds, finish any track entirely in second gear. Checkpoints and Traffic must be turned on for this to work. You can say goodbye to that gearbox.