When the main menu is showing, use the key pointer and click on the two letter I's in driving. When you start the game, your vehicle will not go off of the side of the track, but it can be hit by other cars.

On the selection screen, click with the mouse pointer on the two "I"s in the word driving (perhaps it's "drIvIn"). When you're ready to start, hold down the 'HELP' key until the game has finished loading. You should now see the words "YOU CHEAT" appear in the nationality boxes of the races, and you'll qualify for the next race regardless of the position you finish in. When you start the game, your vehicle will not go off of the side of the track, but it can be hit by other cars.