Over the previous five years, the battle for supremacy at the Circuit de la Sarthe has been waged between diesel-fueled and factory-backed efforts from automotive giants Audi and Peugeot. The 79th running of the 24 Heures du Mans in 2011 marks a continuation of this rivalry but with one distinct difference: for the first time both manufacturers are debuting a new car in the same year.

Audi debuted their first diesel challenger, the R10, in 2006; Peugeot joined one year later with their 908 HDi-FAP. Despite always having pace over their rivals it was not until 2009 that Peugeot defeated Audi. That year Audi had introduced a new car, the R15, to attempt to reduce the speed differential to the 908 HDi-FAP, but its development was insufficient and the car lacked reliability. In 2010 the R15 was so significantly upgraded that Audi dubbed it the R15+; Peugeot carried on with their original car, now four years old and well developed. In a memorable race where the French team flexed its muscle over their German counterparts, putting time into them seemingly at will, it was their older, reliable car that was to falter by the end. One by one, the engines of the 908 HDi-FAP failed in a spectacular, fiery fashion. Analysis showed that the cool air, dry track, and fast pace led all three engines to succumb to a connecting rod failure. It was an epic, and very public, failure. Audi went on to finish 1-2-3. After four years and despite always being faster than the Audi effort, Peugeot's 908 HDi-FAP would score only the one win.

For 2011 the governing body of the 24 Heures, the Automobile Club de l'Ouest, changed the rules over the four classes of automobiles. With the exception of grandfathered models, both the top-tier LMP1 prototypes and the slower LMP2 prototypes have smaller capacity engines limited to 8 cylinders. The GT class is now limited to cars that were formerly known as GT2. The class is now named GTE and split into a "Pro" class for lineups of all professional drivers and the "Am" class for one-year old models with gentlemen drivers.

For the main protagonists seeking to win the race outright, the rule changes necessitates a new car; both Audi and Peugeot have arrived with just that. The Audi R18 is a new philosophy for the manufacturer; unlike all of their successful prototypes of the past the R18 is a coupe. It is powered by a V6 diesel engine with one turbocharger and has a body that can only be described as "purposeful." The Peugeot 908, despite being a completely new car, looks very much like the old 908 HDi-FAP. A roof-mounted air scoop offers the primary visual difference between the two though there are many other changes, including the twin turbo diesel V8.

Earlier in the year, at the 1000 kilometer race at Spa, Audi and Peugeot raced head to head with their new hardware. Peugeot won the race but the Audi R18 was faster. At the Le Mans test day, the R18 was faster. During qualifying for the race proper, the R18 was faster. For the first time in their now five years of head to head competition, Audi finally has a car that is faster than the one from Peugeot. That difference is measured tenths of a second. In this years race of two brand new cars the difference between the two has never been less.

Aston Martin Racing also debut a new LMP1 car in 2011. Their AMR-One is a open cockpit prototype powered by a diminutive 2 liter, straight 6, turbocharged gasoline engine. Unfortunately the program was very late to start and development has been slow. During the test day, one car made it nine laps before the engine expired, the other car completed just two. They've yet to lose an engine during 10 hours of practice and qualifying but their lap times are nailed to the floor of all prototype entries.

Other notable entries in the LMP1 class include the 12 hours of Sebring winner, a grandfathered 908 HDi-FAP from the privateer team Oreca; a pair of Toyota powered Lola Coupes from Rebellion; previous LMP2 competitors Quifel ASM step up to LMP1 in their Zytek, a grandfathered Lola-Aston Martin from the all-Belgian Kronos team; a pair of Judd powered Pescarolo's from Oak Racing; and finally, the very popular return of Henri Pescarolo's #16 team.

LMP2 is stacked with talented teams. Strakka Racing return as last years champion in their HPD; stalwarts RML are competing with an HPD as well. Last years runner up, Oak Racing, return with a pair of Pescarolo-Judd's. Favorites in this class however are the Nissan-engined Oreca chassis's under the banners of Signatech and Oreca-Matmut.

In GTE-Pro, the new Ferrari 458 was thought to be the weapon of choice in 2011. It is likely one may make the podium come Sunday afternoon, for there are seven of them, but it is the two BMW M3's that have led the field qualifying. The German team has held their cards close to the vest this year after showing great pace in 2010, before then being given an air restrictor penalty in the lead up to last years 24 Heures. They were nowhere come race day and have not made the same mistake in 2011. Favourites among the aforementioned Ferrari 458s are from AF Corse, Luxury Racing, JMW Motorsport, and Hankook-Farnbacher. Porsche is again best represented by a pair of cars from Felbermayr and a single entries each from IMSA Performance and Flying Lizard. Corvette Racing is back of course and very much like their chances despite being only fourth fastest in qualifying. Since 1999, only once has Corvette Racing been fastest in their class at Le Mans. They've won six times. New this year is a pair of Lotus Evora's entered by Jetalliance; they won't feature but

Main GTE-Am protagonists include team cars to those named above, AF Corse, Felbermayr, and Flying Lizard plus a Corvete from Larbre Competition, an Aston Martin Vantage from Gulf AMR, and Ferrari's from Krohn Racing, CRS Racing, and JMB Racing. Lastly, the Doran-built Ford GT makes a very popular debut at le Circuit de la Sarthe in the hands of ALMS competitors Robertson Racing.