A Le Mans Prototype is a type of sports prototype race car most notably used in the 24 Hours of Le Mans, American Le Mans Series and Le Mans Series. Created by the Automobile Club de l'Ouest (ACO), they are the fastest closed-wheel racing cars used in circuit racing today, considered a class above production-based grand tourer cars which compete alongside them in sports car racing. Their cost and technology makes them comparable to Formula One cars, including reaching higher maximum speeds than Formula One. Although most commonly known as Le Mans Prototypes, these types of cars have used various names depending on the series in which they compete. The FIA's equivalent cars were referred to as Sports Racers (SR) or Sports Racing Prototypes (SRP). The American IMSA GT Championship termed their cars World Sports Cars (WSC), while the short-lived United States Road Racing Championship used the classic Can-Am (CA) name for their prototypes. Since 2004, all series have switched to referring to these cars as Le Mans Prototypes.