IROC I was the inaugural International Race of Champions, which was held at two tracks over two weekends in 1973 and 1974. The first three races were held October 27 and 28, 1973 at Riverside International Raceway and the final race was held on the Daytona International Speedway road course on February 14, 1974. Champion Mark Donohue won $54000 and the championship, which was determined by prize money rather than points. The races were contested in Porsche Carrera RSR race cars. This was the only IROC to be contested entirely on road courses. Only the top 6 finishing drivers competed in all four races. The roster of drivers and final points standings were as follows: Note: Jackie Stewart was originally scheduled to compete but retired from racing two weeks prior to the first race. He was replaced by A.J. Foyt, who had previously declined an invitation saying the all road course format was unfair to oval racers.

Race results

Riverside International Raceway, Race One

Riverside International Raceway, Race Two

Riverside International Raceway, Race Three

Daytona International Speedway, Race Four