Start the game, then hold the left mouse button, fire button, and type
"GROWLER". Press 'T' for more time.

Also after Nancy has told you about the car you are after, keep pressing
the SPACE BAR repeatedly very fast until the game comes on. Your car should
be doing over a 1000 KMH. Before each new level finishes talking, hit space
and use a free nitro. The X & Z keys make steering easier.