the intervals between cars increase. This decreases the chance of crashes but increases the damage and chance of injury when cars do crash. United Kingdom In Great Britain the oval tracks are normally on grass with lengths of 400 meters (¼ mile) to 800 meters (½ mile). The races consist of several four lap qualifying heats that eliminate slower drivers. Then there is a final race featuring the fastest competitors. Europe In mainland Europe, long tracks can be grass, sand or cinder, and can be up to long. Australia Dirt track racing in Australia has a history dating back to the 1920s and 1930s. Most oval track speedways are similar to those in the US for car racing such as sprint cars, speedcars (midgets) and sedans, with most tracks generally around ¼ mile (402 m) to ⅓ mile (536 m) in length. Most tracks have a clay surface, though some use dolomite, dolomite and clay mix or even sand and clay mix. During the 1970s and early 1980s, a small number of tracks were paved with asphalt, though this phase only lasted about a decade and all tracks paved over eventually reverted to their former surfaces. Race vehicles Each racetrack or sponsoring organization maintains a rule book outlining each class of race car which includes dimensions, engine size, equipment requirements and prohibitions. The requirements for each class are usually coordinated with multiple tracks to allow for the widest available venue for each type of car. This coordination allows the drivers to compete at many different racetracks, increase competitors' chances of winning, and lets racing associations develop a series of race events that promote fan interest. Many tracks support two types of racing in their programs, open wheel cars and stock cars. Both types range from large and powerful V8 engines to small yet still powerful, four-cylinder engines. Some of the smaller open wheel race cars have classes for single-cylinder engines. Depending on the class, the cars may have wings to aid in handling at higher speeds. Open wheel cars Open wheel cars are generally manufactured with tubular frames and a body purchased for that particular class. The wheels of these vehicles are not protected by fenders; they are exposed or "open". Classes include: Dwarf (5/8 replicas of 1928 to 1948 coupes and sedans) Mod lite - 1000-1250cc motorcycle engines (5/8 replicas of full size modified but equally as fast) Kart