Stock car racing is a form of automobile racing found mainly in the United States, Canada, New Zealand, Great Britain and Brazil. Traditionally, races are run on oval tracks measuring approximately ¼ mile to 2.66 miles (about 400 meters to 4.2 kilometres) in length, but are also raced on road courses[citation needed]. The National Association for Stock Car Auto Racing (NASCAR) is the world’s largest governing body for stock car racing, and its Sprint Cup Series (named for its sponsor, Sprint Nextel Corporation) is the de facto premier series of stock car racing. Top level races are 200 to 600 miles (320–1000 km) in length. Average speeds in the top classes are usually within 70-80% of comparable levels of open wheel racing at the same tracks. Some stock cars may reach speeds of in excess of 200 mph (320 km/h) at tracks such as Indianapolis Motor Speedway and Lowe’s Motor Speedway. For safety, devices such as restrictor plates may be used at Daytona International Speedway and Talladega Superspeedway that limit top speeds to approximately 187 mph (301 km/h).

Open-wheel car, formula car, or often single-seater car in British English, describes cars with the wheels outside the car’s main body and, in most cases, one seat. Open-wheel cars contrast with street cars, sports cars, stock cars, and touring cars, which have their wheels below the body or fenders. Open-wheel cars are usually built specifically for racing, frequently with a higher degree of technological sophistication than in other forms of motor sport. A few specialty open-wheel cars are built for both street and track; the best-known is probably the Lotus Seven/Caterham Seven.