When the first oval speedway built for automobile racing was constructed in England in 1906, ordinary street cars were the vehicles of choice for racing. These cars were typically procured directly from dealerships, with minimal alterations made to meet the demands of the racetrack. The affordability and accessibility of stock cars allowed racing enthusiasts from all walks of life to participate, contributing to the growth and popularity of the sport. As the sport evolved, so did the modifications made to the stock cars. Drivers started customizing their vehicles by enhancing performance and safety features, such as reinforcing chassis frames, installing roll cages, and improving engines and suspension systems. These modifications allowed the stock cars to withstand the intense demands of racing, turning them into formidable competitive machines. Requirements for these introductory divisions can vary greatly, but all are based on a full-bodied passenger vehicle and an
original equipment manufacturer (OEM) production engine. Roll cages must be welded into the frame, and all glass, vinyl, upholstery and lights must be removed from the vehicle. In various regions, they may be known as hobby stocks, street stocks, pure stocks, bombers, factory stocks or stingers. In British
oval racing, the term "production car racing" has been used as an alternative for
hot rods, as run in the
West Country during the late 1960s to the mid-1970s, and a production car world championships. The West Country production cars were later reclassified as hot rods to come in line with the country's other promoters although this causes some confusion with the history of the West country racing as there was another class called hot rods that ran on those tracks. The major U.S. sanctioning organizations –
International Motor Contest Association (IMCA),
DIRTcar,
NASCAR, and
Championship Racing Association (CRA/ASA) -- generally promote these classes as one of three levels: entry, intermediate, or advanced.
Entry-level The Sport Compact (IMCA, DIRTcar) or Pure Stock (NASCAR) or Mini-Stock or Bomber divisions are the lowest entry-level racing class. Four-passenger vehicles with a four-cylinder or limited six-cylinder engines, the rules for these race cars mandate a stock body and a stock suspension. The vehicles can be made race ready for $500 to $2,000, and involve merely gutting the interior and adding a racing seat and roll cage.
Intermediate The Hobby Stock (IMCA) or Factory Stock (DIRTcar) or Thunder Car (NASCAR) are also divisions designed to give new competitors the chance to go racing. The body and frame must match, and very few alterations are allowed to the stock frame and suspension. The engines produce roughly 300 horsepower and must reflect the correct pairing to the model. Racers can generally build competitive cars for between $3,500 and $10,000.
Advanced The Stock (IMCA, DIRTcar) or Street Stock (NASCAR, CRA/ASA) or Pro Stock (DIRTcar Northeast) divisions characteristically have bigger engines that produce roughly 360 horsepower, yet still require an OEM passenger vehicle production block. The rules also allow for some changes to the suspension, including the addition of screw jacks. While a used race car can be purchased for around $6,500, competitive stock cars can cost upwards of $25,000. ==Touring car racing==