Cheat mode: 
     At the Main Menu, enter icancheat to enable cheats. Now enter the
following codes on the specific screens:

Main Menu:

clipped                 No clipping mode
reckless                Reckless mode

Track selection:
                              
freeride                More tracks 
freedrive               Even more tracks  
lapset                  Set number of laps
                     
Car selection:
                           
redfury                 Jeff Gordon's car
takemeon                Expert mode
widebodyopen            Xwave car
wildone                 Wraith car