Sports car racing is a form of motorsport road racing which utilises sports cars that have two seats and enclosed wheels. They may be purpose-built (Prototype) or related to road-going models (Grand Touring). Broadly speaking, sports car racing is one of the main types of circuit auto racing, alongside open-wheel single seater racing (such as Formula One), touring car racing (such as the Deutsche Tourenwagen Masters, which is based on 'saloon cars' as opposed to the 'exotics' seen in sports cars) and stock car racing (such as NASCAR). Sports car races are often (though not always) endurance races that are run over relatively large distances, and there is usually a larger emphasis placed on the reliability and efficiency of the car (as opposed to outright speed of the driver) than in some of the other types of auto racing. The FIA World Endurance Championship is an example of a sports car racing series.