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.
Try hitting the cow for a surprise!