XTreme Racing

On the 1st selection screen type any of the following:

   SHEEPY SHEEPY         For a sheep as a vehicle.
   TURBO NUTTER BASTARD  ????
   IDKFA                 For auto qualify.
                         (and access to 3 bonus tracks in single track mode)

HINTS:

Grassland 1 has a short cut - where you have the blocks in the middle
of the road.  Go just past there and you can drive through a tree.