12 Hours of Sebring

The track opened in 1950 on an airfield and is a road racing course styled after those used in European Grand Prix motor racing. The first race was a six-hour race on New Year's Eve 1950; the winning car is on display at the Edge Motor Museum in Memphis, Tennessee. The next race was held 14 months later as the first 12 Hours of Sebring. The race is famous for its "once around the clock" action, starting during the day and finishing at night. In its early years, the Sebring circuit combined former airport runways with narrow two-lane service roads.

From 1953 to 1972 the 12 Hour was a round of the FIA's premier sports car series, which was contested under various names including the World Sportscar Championship and the International Championship for Makes. In the 1950s, in addition to Le Mans, Sebring shared the World Sportscar Championship calendar with now-legendary races such as the Mille Miglia, the Targa Florio, the Carrera Panamericana and the RAC Tourist Trophy, such was the prestige of the Sebring race.

It was also the most important American race for European teams and drivers and was the center of European racing activity in the United States; it was the only time during the 1950s that the big European manufacturer teams and drivers came to the United States in force, bringing considerable international media attention—the United States Formula One Grand Prix was not run until 1959. Top drivers who competed on the European circuit in the 1950s, such as Juan Manuel Fangio, Alberto Ascari, Nino Farina, Stirling Moss and Mike Hawthorn, all raced at Sebring, and the 1957 Sebring 12 Hours was the only American race the five-time world champion Fangio ever won.

The 1966 event was a turning point in Sebring history, as the facilities and the safety of the circuit were heavily criticized. Five people were killed during the race, more than in the race's prior 15-year history combined. Bob McLean crashed while approaching the hairpin; his car rolled several times, struck a utility pole and then exploded, landing in a ditch and killing him. In another incident Mario Andretti in his Ferrari 365 P2 tangled with Don Wester's Porsche 906 on the Warehouse Straight near the Webster Turns, killing four spectators and then crashing into a warehouse next to the track. Subsequent to these events, the facilities were upgraded and the circuit layout was changed, including eliminating the Webster Turns and creating the Green Park Chicane further down the track to move the straight further away from the airport warehouses. The circuit was made safer, and there have only been four fatalities since then—a remarkable record for a circuit of Sebring's age.

The same 1966 race had Dan Gurney leading on the last lap when the engine of his Shelby American Ford GT40 Mk II seized near the end. Gurney pushed his car over the finish line, beaten only by Ken Miles and Lloyd Ruby. However, his actions were ultimately determined to be against the rules and he did not receive credit for his finish.

Races up until 1969 began with the traditional Le Mans start procedure, which was abolished at the end of the 1969 season following Jacky Ickx protesting at Le Mans in 1969; 1970 was the first 12 Hours of Sebring started with a rolling start.

The race is known as preparation for the 24 Hours of Le Mans, as the track's technical layout and extremely bumpy surface, combined with south-central Florida's perennial hot weather, is a major test of a car's reliability. Teams planning to compete at Le Mans regard Sebring as an ideal preparation run for the prestigious French race.

In 2005, the Chevrolet Corvette C6.R and Aston Martin DBR9 made their race debut in the hotly contested GT1 class, with Aston Martin winning its class for the first time in 49 years at Sebring ahead of the two Corvettes. Corvette had dominated the class the past three years with its previous-generation C5R. The all-new Audi R10 TDI won the 2006 edition of the race, the car's first ever run in competition; the much-hyped Porsche RS Spyder campaigned by Penske Racing dropped to second place in its LMP2 class, behind the Intersport Lola car, while the GT1 Corvette C6R team got their revenge against the Aston Martin. In 2007 Audi again won in the R10 TDI despite requiring more frequent refueling due to changes in American Le Mans Series rules intended to even the field between gasoline and diesel-powered engines.

In recent years, six overall victories have been achieved by the Audi R8, one fewer than the record seven wins of the Porsche 935. Tom Kristensen has won the race more times than anyone else, with six victories—in 1999–2000, 2005–2006, 2009 and in 2012.

Technically the race "winner" in 1950 was the Crosley Hot Shot of Fritz Koster and Ralph Deshon, entered by Victor Sharpe Jr. of Tampa. While the Wacker/Burrell Allard covered more distance, the race was run under the "Index of Performance" handicapping rules and the Crosley, with a much smaller engine than the Cadillac-powered Allard, is listed in the Official Sebring Record Book as the winner.

The race has been a round of the now-defunct World Sportscar Championship, the IMSA GT Championship and the American Le Mans Series. In 2012, the race was the opening event of the FIA World Endurance Championship in a one-off race before being returned to the American Le Mans Series for 2013. Starting in 2014, the event became the second round of the WeatherTech SportsCar Championship. In 2020 the race was rescheduled to mid-November due to delays caused by the pandemic; it was the only season where Sebring was run twice in a season, after a three-hour race was held in July with spectators as part of restarting the season.

This article is based solely on the supplied corpus. No external sources were consulted; claims that could not be substantiated against the corpus were omitted under the drop-the-claim rule.