In motorsport, a safety car or pace car is a car which limits the speed of competing cars on a racetrack in the case of a caution period such as an obstruction on the track. During a caution period the safety car enters the track ahead of the leader. Competitors are not allowed to pass the safety car or other competitors during a caution period, and the safety car leads the field at a pre-determined safe speed, which may vary by series and circuit. At the end of the caution period, the safety car leaves the track and the competitors may resume racing.