Unlimited Fuel
In any Grand Prix race, set your fuel to 10% before starting to get max acceleration and don't worry you dont lose any fuel during the whole race!
Bonus Car
After you've become World Grand Prix Champion, turn on the system and hold A + B when the screen "Now loading the data from controller pak..." Now go to the Driver Selection screen and the '96 Forti drivers will now have an Ubi Soft Original H-RA V12 Car.
Note: You need a controller pak to do this code.