Hillclimbs and Sprints are very similar in concept and operation. A wide variety of cars compete from standard road saloons to Formula 1 cars, divided into classes by type and engine capacity. The cars run singly, over a clearly defined smooth sealed surface, timed electronically to a high degree of accuracy. All cars must comply with MSA regulations and a crash helmet and flame-resistant overalls will also be required. Venues for these events range from disused airfields to permanent racing circuits, and from private estates to seaside promenades.