24 Hours of Le Mans

The 24 Hours of Le Mans (French: 24 Heures du Mans; French pronunciation: [vɛ̃t.katʁ‿œʁ dy mɑ̃]) is an endurance sports car race held annually near the city of Le Mans, France. It is widely considered to be one of the world's most prestigious races, and is one of the races – along with the Monaco Grand Prix and Indianapolis 500 – that form the Triple Crown of Motorsport, and is also one of the races alongside the 24 Hours of Daytona and 12 Hours of Sebring that make up the informal Triple Crown of endurance racing. Run since 1923, it is the oldest active endurance racing event in the world.

Unlike fixed-distance races whose winner is determined by minimum time, the 24 Hours of Le Mans is won by the car that covers the greatest distance in 24 hours. The cars on this track are able to achieve speeds of 366 km/h (227 mph), and reached 407 km/h (253 mph) on the Mulsanne Straight in 1988 – instigating the addition of more chicanes to the track to reduce speed reached. Racing teams must balance the demands of speed with the cars' ability to run for 24 hours without mechanical failure. The race is organized by the Automobile Club de l'Ouest (ACO). It is held on the Circuit de la Sarthe, composed of closed public roads and dedicated sections of a racing track.

The 24 Hours of Le Mans was often part of the World Sportscar Championship from 1953 until that series' final season in 1992. In 2011, it was a part of the Intercontinental Le Mans Cup. Since 2012, the race has been a part of the FIA World Endurance Championship. A 10-hour American version of the race, called Petit Le Mans, has been held annually since 1998.

Launched when Grand Prix motor racing was the dominant form of motorsport throughout Europe, Le Mans was designed to present a different test. Instead of focusing on the ability of a car company to build the fastest machines, the 24 Hours of Le Mans would concentrate on the ability of manufacturers to build sporty yet reliable cars. This encouraged innovation in producing reliable and fuel-efficient vehicles, because endurance racing requires cars that last and spend as little time in the pits as possible.

At the same time, the layout of the track required cars with better aerodynamics and stability at high speeds. While this was shared with Grand Prix racing, few tracks in Europe had straights of a length comparable to the Mulsanne. Additionally, because the road is public and thus not as meticulously maintained as permanent racing circuits, racing puts more strain on the parts, increasing the importance of reliability.

The oil crisis in the early 1970s led organizers to adopt a fuel economy formula known as Group C that limited the amount of fuel each car was allowed. Although it was later abandoned, fuel economy remains important as new fuel sources reduce the time spent during pit stops. Such technological innovations have had a trickle-down effect and can be incorporated into consumer cars. This has also led to faster and more exotic supercars as manufacturers seek to develop faster road cars in order to develop them into even faster GT cars.

Additionally, hybrid systems (flywheel, super-capacitor, battery coupled with both petrol and diesel) have been championed in the Le Mans prototype category as rules have been changed to their benefit and to further push efficiency.

The race is held in mid-June, near the summer solstice, meaning the shortest night and very hot conditions for drivers, particularly in closed vehicles with poor ventilation. Rainy weather is common. The race begins in mid-afternoon and finishes the following day at the same hour the race started the previous day.