Speed Circuit was an Avalon Hill game (previously published by 3M), currently (2009) out of print. The 3M edition featured the grand prix circuits of Monaco, Monza and Watkins Glen. and was first published in 1971.
Its solid body of rules allowed a lot of optional house rules. Also, a lot of players could be involved, with races of up to twelve cars usually being very competitive and rewarding for the players.
Another advantage was the release of extra tracks by Avalon Hill, to allow the running of championship seasons, and the relative facility for players to design their own tracks.
The game was based on a points distribution system to specify characteristics of each car: Start Speed, Acceleration, Deceleration, Top Speed and Tire Wear. Each space moved was equal to 20 MPH.
While Speed Circuit is out of print the game is still actively played at boardgame conventions such as PREZCON held in Charlottesville, VA, annually in February and at WBC (World Boardgaming Championships) held in Lancaster, PA, annually in July/August. Novice players are welcome to learn the game at these events.