In recent years motor racing has become one of the most popular of sports, attracting record numbers of followers. In some racing categories the vehicles resemble production sedans while in others they look more like fighter airplanes, and there is also a great variety of tracks that range from paved to unpaved and from straight to oval or regular road courses. In all forms of racing, however, aerodynamics eventually surfaced as a significant design parameter, and nowadays all race-car designs have some level of aerodynamic element.