Hard Drivin'
Get to full speed (preferably but not
necessary) and press 'N' for neutral. Now
you can cruise along at full speed with
easy steering and invulnerability. As
long as you stay in neutral you will have
unlimited time as well.
Another trick is to repeatedly hit the 4
key (4th gear) until the program has an
error. Continue with the right mouse
button. Repeat until you get a high score.