The 2011 24 Hours of Le Mans (24 Heures du Mans 2011) was the 79th Grand Prix of Endurance, and took place on 11–12 June 2011 at the Circuit de la Sarthe, Le Mans, France, and organised by the Automobile Club de l'Ouest (ACO).
It was the third round of the 2011 Intercontinental Le Mans Cup, and was part of a World Championship or International Cup for the first time since 1992, when it was part of the World Sportscar Championship. Early accidents eliminated two of Audi's three entries, but the sole remaining Audi R18 TDI of Tréluyer, Marcel Fässler, and André Lotterer held off the trio of Peugeot 908s and a Peugeot 908 HDi FAP to claim victory by a margin of 13.8 seconds.
Greaves Motorsport Zytek-Nissan won the LMP2 category, Corvette Racing secured the GTE Pro class victory, and Larbre Compétition claimed a one-two finish in the GTE Am category with Corvette and Porsche.
The new ACO rules meant that the previous LMP1 cars (2007–2010) were rendered obsolete. Engines in the LMP1 cars were similar to the engines in the LMP2 cars prior to 2010 (maximum engine sizes were: 3.4 L (3400 cc) for naturally aspirated engines; 2.0 L (2000 cc) for turbocharged petrol engines; 3.7 L (3700 cc) for turbocharged diesel engines).
For 2011, cars raced during the 2010 season in an ACO-sanctioned event could participate, but would need to run smaller air restrictors, less boost pressure (turbo and turbo diesel), and a smaller fuel cell.
LMP2 engines were reduced to those similar to GT2; the engines would be production-based (maximum engine sizes were: 5.0 L (5000 cc) for normally aspirated engines, 8 cylinders maximum; 3.2 L (3200 cc) for turbocharged engines, 6 cylinders maximum; diesel engines were not permitted).
LMP2 were also focused on lower costs: the price cap for an LMP2 car was set at €400,000 (€325,000 for chassis, €75,000 for engine).
Lola Cars International was the first manufacturer to announce two different LMP2 cars, the open cockpit B11/40 and the closed cockpit B11/80; BMW, Ford, Honda (HPD), Jaguar, Nissan and Toyota engines could be fitted into a B11/40.
Hybrid vehicle drivetrain systems were extensively allowed with the new regulations, which included kinetic-energy recovery systems (KERS; no push-to-pass systems – KERS in LMP cars must be activated with the accelerator pedal), as well as four-wheel drive (non-hybrid vehicles would remain two-wheel drive, specifically rear-wheel drive).
All LMP cars were to weigh in at 900 kg (2,000 lb).
In addition, LMP bodywork was to have a vertical fin on the top of the engine cover in order to reduce lift tendency and airborne crashes such as the 1999 race where Mercedes-Benz CLRs driven by Mark Webber and Peter Dumbreck repeatedly crashed, and the 2008 1000 km of Monza crash of a Courage-Oreca LC70 driven by Stéphane Ortelli.
The former GT2 class became the sole production-based category in 2011, renamed as GT Endurance category and was separated into two subclasses - GTE Amateur (GTE Am) and GTE Professional (GTE Pro) - with a trophy each class.