"In the scene where you choose to go to map select, vehicle select, start race etc, type ENABLE to be given access to all tracks and vehicles. You can now use all of the other cheats in the game
When the race starts, press F4 and find cheat mode. Now use these cheats:
F5 -Total repair (free)
F6 -Toggle Invulnerability on/off
F7 -Adds 30 seconds to the timer
F8 -Freeze/Unfreeze timer
F10 -Increment lap counter
F11 -Earn 5000 credits instantly
SHIFT-F6 -Show opponents on map
SHIFT-F7 -Adds 300 seconds to timer

Also try these:
# (any number)
SHIFT-#
ALT-#
SHIFT-ALT-#
CTRL-#"
