The Mulsanne Straight is, outside of race week, an ordinary public road forming part of France's national road network — route départementale RD 338, formerly Route Nationale RN 138 in the Sarthe department. The French name, Ligne droite des Hunaudières (literally "Straight Line of Les Hunaudières"), refers to the hamlet of Les Hunaudières through which the road passes. The English name derives from the village of Mulsanne at the end of the straight, where the road meets a sharp right-hand corner before continuing toward Arnage.
The straight was incorporated into the Le Mans circuit from its earliest days. After the circuit's classic layout was established in the 1930s — adding a bypass from the pits via the Esses to Tertre Rouge — the straight formed almost half of the lap distance. Cars exited Tertre Rouge and accelerated down the Hunaudières at full throttle for close to three kilometres before braking hard for the tight right-hander at Mulsanne village.
The straight includes a slight right-hand curve near its end, known as the "Kink," which became notorious in the 1980s as speeds rose dramatically. Speeds during this era regularly reached and exceeded 400 km/h (250 mph). The Porsche 917 longtail — the dominant car of 1970 and 1971 — reached 362 km/h (225 mph). Turbocharged Group C prototypes of the late 1980s pushed even higher: the 1978 Porsche 935 was clocked at 367 km/h (228 mph) and at the 1988 race, Roger Dorchy in the Welter Racing WM P88 — powered by a 2.8-litre turbocharged Peugeot PRV V6 running well beyond its normal output — was measured by radar at 405 km/h (252 mph), an all-time record for the straight.
The unrestricted Mulsanne Straight claimed lives and machinery throughout the 1980s. Jean-Louis Lafosse was killed there in 1981, and Jo Gartner in 1986. In 1984, a French track marshal died in an accident at the Kink involving two Aston Martin Nimrod NRA/C2s. One of the most dramatic escapes came in 1986, when Win Percy's Jaguar XJR-6 suffered a tyre blowout at 386 km/h (240 mph), flipping the car high into the air; the wreckage came to rest 600 m down the road and Percy walked away with only a damaged helmet.
Following a ruling by the FIA that it would no longer sanction circuits with a straight longer than approximately 2 km (1.2 mi) — roughly the length of the Döttinger Höhe on the Nürburgring Nordschleife — two chicanes were added to the Mulsanne Straight before the 1990 24 Hours of Le Mans. The interruptions broke the formerly 6 km (3.7 mi) continuous blast into three shorter sections, reducing peak speeds to approximately 330 km/h (205 mph) during qualifying and 320 km/h (199 mph) in the race.
Since 1990, the highest speed recorded on any section of the straight was achieved during qualifying by a Nissan R90CK driven by Mark Blundell, which reached 366 km/h (227 mph) after a stuck wastegate caused the twin-turbo engine to produce far beyond its rated output. In the 2025 race, the highest peak speed was 349 km/h (217 mph), set by Antonio Giovinazzi in the Ferrari 499P on lap 64.
The Mulsanne Straight became symbolic of everything that made Le Mans unique: the sheer duration of the event combined with the requirement to sustain maximum velocity for extended periods put extraordinary stress on engines, tyres, and drivers. The name entered broader automotive culture through Bentley, which named three models after places along the circuit: the Mulsanne, the Arnage, and the Hunaudières concept car. General Motors also offered a 1970 Corvette in a colour called Mulsanne Blue.
Even after the chicanes reduced its character, the straight remains the centerpiece of the Le Mans lap — the point where prototype power is most viscerally demonstrated and where the lap's rhythm is set.