Audi, the dominant force at Le Mans since the turn of the century, faces a stern challenge from Porsche this year. The 919 hybrids locked out the front three grid spots, with the Audi challengers fourth, fifth and sixth.
For many years, the Volkswagen subsidiaries Porsche and Audi stayed out of each other's way in endurance racing. While Audi dominated the fastest LM P1 (Le Mans Prototype 1) class, claiming 13 of 15 outright Le Mans wins since the turn of the century, Porsche was happy to focus on its near-roadgoing models competing in the lower GT classes of the field.
This weekend's gruelling 24-hour race will be the second where Porsche seeks outright victory at Le Mans, fielding its new 919 Hybrids. Only reliability robbed Porsche of a debut win in 2014, and in 2015, the 919s will start first, second and third on the grid.
Neel Jani, sharing the number 18 Porsche with Romain Dumas and Marc Lieb, set the fastest time of all in qualifying.
"To be in pole position in the 24 Hours of Le Mans, with a mythical brand such as Porsche, is exceptional," said the 31-year-old Swiss. Jani, who leads from the front, recorded a time of three minutes 16:887 seconds, which was a new qualifying record for an LM P1 car.
Porsche win one-lap battle, ahead of 24-hour war
Mark Webber propelled car 17 to second on the grid and German F1 driver Nico Hülkenberg set the third-fastest time in the number 19 Porsche.
"Porsche is synonymous with success here," former Formula One driver Mark Webber said. "It's a great burden for us to carry, we're proud of that, but it's not something that will guarantee us results on Sunday."
The Audi R15s lock out the following three grid spots, with last year's winning trio - Andre Lotterer, Marcel Fässler and Benoit Treluye - set to start sixth on the grid. They claimed Audi's eighth win in nine attempts last time around as the stricken lead Porsche languished in the pits with mechanical problems.
Pride of Endurance season
The 83rd edition of Le Mans 24, the jewel in the crown of the FIA's World Endurance Championship (WEC), starts on Saturday afternoon, to finish a full day later.
"It's a huge event and a festival. Everybody's camping in the middle," explained Martin Brundle, the winner of the race in 1990, referring to the fans who fill the high-speed circuit's infield for the weekend. "The track is mildly terrifying at all times and especially in the middle of the night, in the rain, with oil on it or gravel or pieces of other car. It's a scary racetrack."
Drivers will be under pressure in one of the world's few remaining motor racing events to run for a full 24 hours. There are 38 corners on the track and around 80% of the lap is spent at full throttle, leaving little margin for error when making split-second decisions.
"It's just the immensity of it. What is it - 5,000 kilometers or 3,500 miles in a day?" Brundle said. "It's extraordinary. If you look at the number of people in a team, and 28 scheduled pitstops or something like that, the logistics make F1 look puny."
Audi could win its sixth title on the spin, equaling the second best record by Ferrari and drawing within one of Porsche - who won seven on the bounce between 1981 and 1987.