Turbo
Ah, the world's least intuitive
and player-friendly turbo function! If you need extra speed in the race,
hold down A to accelerate, make a hard turn in either direction while holding
Z, then release both buttons. If by some miracle you've got your timing
right and haven't sent your car into a wall, you'll get a burst of extra
speed. You can keep using the turbo until the temperature gauge rises too
high.
Secret Cars and Tracks
When the start screen appears,
on controller two push and hold Up on the d-pad, then press R, L, Z and
C Down simultaneously. You should now be able to play with extra vehicles
on a new track.