1983 marked the second year of Chevrolet having major competition, with Cosworth taking second at Mosport,[1] first at Lime Rock,[2] second at Trois-Rivières,[3] first at the second race at Mosport,[4] and second at Sears Point.
Porsche would get its first podiums this season, with a win at Road America[6] and third at the second race at Mosport.
The dominant chassis were Frissbee, Ensign, Lola, VDS, Scandia, and Ralt.
Jacques Villeneuve, Sr. was declared champion, with podiums in almost every race.
Bertil Roos won his second straight two liter class championship.