Iroc

The International Race of Champions series was beloved by NASCAR and international fans alike, as drivers from several different disciplines could be seen competing on a level playing field. During the hiatus of motorsports due to the COVID-19 pandemic in 2020, an all-star cast of drivers competed in iRacing in dirt modifieds, GTE cars, and stock cars. Dubbed a "tribute to IROC", the event included drivers from NASCAR, NHRA, IndyCar, IMSA, Supercross, Supercars Championship, Formula One, and Rallycross.

In 2007, IROC could not find a sponsor and postponed the first two races at Daytona and Texas. IROC went on hiatus in 2007 hoping to return with a sponsor in 2008, which did not happen. In March 2008, IROC auctioned off its tools, equipment, cars, and memorabilia, and went out of business.

In 2004, the alcoholic beverage company, Diageo became the series' title sponsor, utilising their Crown Royal brand whiskey, replacing True Value, and the procedure changed, as well. Cars would be identically painted in white, with trim which could be changed to represent the driver's colors in his regular racing series. Also, a driver's number in IROC would be his regular number. Thus, Steve Kinser would use green trim with the No. 11, and Matt Kenseth's car featured yellow trim with a 17.

Through 2003, IROC was also known for its rainbow of car colors being easily recognized from all other racing series. Car numbers were utilized for scoring purposes, but were not the primary means of identification. Instead, the drivers' surname would appear on the door of the car. Exceptions were made when Mario and Michael Andretti raced in the same events. In those cases, their first name was used. The numbers would change from race to race, with the number 1 would be given to the driver starting first, and so on. The colors would correspond to the numbers. Before the races, drivers were assigned via blind drawing, as was how the starting grid for the first race was determined. The finishing order of the race would be inverted for the second race's starting grid, while the reverse of the points standings determined races three and four's grids. Numbers were assigned by the starting position. After the first race, the numbers would be assigned based on points standings.

The only exception to the numbering scheme involves the number 3. Following the death of Dale Earnhardt in the 2001 Daytona 500, IROC retired the use of No. 3. Any driver with that regular number would use No. 03 instead. Hélio Castroneves raced with No. 03, but the car kept red trim, in reflection of his IndyCar being red.

From 1992 to 2005, the IROC season was exclusively run on ovals. In 2006, road courses were reintroduced to the IROC series with the cars competing on the road course at Daytona International Speedway. Also, in 2006, two drivers shared one car in an IROC first. Grand American Road Racing drivers Max Angelelli and Wayne Taylor each drove two races in 2006, trying to win the IROC title as a team, reflecting sportscar racing as a two-man team. However, in 2007, that may not have been used, as 2006 Grand American Road Racing champion Jörg Bergmeister was a solo champion. Bergmeister had to split driving duties with various drivers because his regular co-driver was forced to sit out three races because they were raced with the Indy Racing League; Colin Braun, who was 17, could not race in those three races under MSA rulings.

From its inception to 1991, the series contested at least one race on a road course. Riverside International Raceway held the most IROC road races, followed by Watkins Glen International Raceway. Races were also contested at Mid-Ohio, the Daytona International Speedway road course, and the Burke Lakefront Airport CART series course.

Due to its fundamental stock car formula, and the majority of racing being contested on ovals, the series was often dominated by NASCAR participants (which was the major criticism of the series). Also, in the small field of about a dozen cars, the share of NASCAR invitees grew over time; from just three drivers in the first season to seven in the final season. The last non-NASCAR based champion of the series was Al Unser, Jr. in 1988. Although open wheel drivers had numerous successes, as of 2005, drivers from road racing series had only won two races in the history of IROC. In some years, no sports car drivers competed.

Drivers raced identically-prepared stock cars set up by a single team of mechanics in an effort to make the race purely a test of driver ability. It was run with a small field of 12 invited drivers. It was created and developed in 1972 by David Lockton, the developer of the Ontario Motor Speedway, launched in 1973, with Mark Donohue being the first driver to win the championship in 1974. The cars used that year were Porsche Carrera RSRs. Donohue's win in the fourth and last race of that season was his last win, as he died in a Formula One crash at the Österreichring in practice for the 1975 Austrian Grand Prix. The series was not run in 1981, 1982, or 1983.