The #7 Audi R18 e-tron quattro of Marcel Fässler, André Lotterer, Benoît Tréluyer finsihed first in the World Endurance Championship Six Hours of Spa, following up on its similar victory in the season-opening Six Hours of Silverstone in April.
Spa was not a wheel-to-wheel, multiple-passes-per-lap pit fight like Silverstone. While there was a lot of overtaking, strategy and reliability played equal parts in determining the winner. While the margin of victory for the #7 Audi was three times as large as at Silverstone—a whopping 13.42 seconds—the tension of the closing laps was just as high, as the different fuel and tire strategies played out.
“What a race,” Tréluyer said in a press statement. “It was a tough lights-to-flag job, just like at Silverstone, but it was huge fun and we’re already looking forward to Le Mans.”
Porsche captured the rest of the podium with the #18 919 Hybrid of Romain Dumas, Neel Jani, and Marc Lieb finishing a mere 13 seconds behind the winning Audi, with the #17 Porsche of Timo Bernhard, Mark Webber, and Brendon Hartley a lap down after losing time to a penalty and a rear suspension problem.
The speeds shown by the Porsches and Audis were simply astounding. The winning car covered 1232.6 km, the greatest distance ever covered in a six-hour motor race—ever. And this is by cars using 40 percent less fuel than they were two years ago.
Le Mans will almost certainly also be a record-setting event this year—and judging from the first two races of the season, it will be 24 hours of non-stop excitement.
Audi’s Efficiency Trumps Porsche’s Pace
Despite being outfitted with low-drag Le Mans bodywork, the #7 and #8 Audis still had enough downforce to make the kind of outside passes it used so effectively at Silverstone; in fact, the low-drag Audis were quickest through the twisty second section of the Spa-Francorchamps track, quicker even than the high-downforce #9 Audi.
Audi won the race not on pace—the Porsches were both quicker and faster on fresh tires—but on strategy. With each team having 26 tires for the weekend, everyone had to double-stint at one point during the race. Audi was gentler to its tires. Knowing this Audi engineer Leena Gade double-stinted the #7 twice, gaining track position while the leading Porsche sat on the jacks, and in the last stint, forcing the Porsche to double-stint in response.
André Lotterer turned in his usual two very fast stints mid-race, before handing off to Benoît Tréluyer on lap 117 with the Audi needing two full stops and a splash. Marc Lieb in the #18 Porsche moved into the lead for one lap, then pitted but didn’t take tires. Lieb came out still ahead, but couldn’t hold off the Audi on old rubber, and had to pit eight laps ahead of schedule, letting Tréluyer into the lead.
Lieb pitted on lap 133 and handed off to Neel Jani while the crew slapped scrubbed tires onto the car for the final two stints. Tréluyer pitted on lap 141, didn’t take tires, and came out 16 seconds ahead of the Porsche.
Jani caught and passed the Audi on lap 156, then pitted and didn’t take tires, gambling on making up the lost performance in track position. Even if the Audi could catch and pass the Porsche in the second sector, the Porsche could power past on any short straightaway. Also, the Audi was already double-stinting its tires; surely when it made its final pit stop, it would need to get fresh rubber, letting the Porsche back by.
Audi engineer Leena Gade had a different idea. Instead of pitting the #7 Audi early, she ran a full fuel stint; she gambled that the Porsche wouldn’t be able to close the gap on old rubber, and she was right. Gade called in Tréluyer on lap 164—for fuel only. having seen how the Porsche performed on old rubber, she decided the Audi could stretch its tires ten more laps and still stay in the lead.
She was right. Tréluyer rejoined 13 seconds ahead of Jani, and the gap never shrank. The Porsche was quicker and faster in a straight line, but the Audi was almost incredibly aerodynamically efficient.
The Aero Advantage
According to Audi motorsports chief Dr. Wolfgang Ullrich, Audi decided at the start of the 2014 season that the 2105 car needed to be slipperier while still having much more downforce than its predecessor. With regulations requiring that the cars be about one-third more fuel-efficient, the easiest way to increase speed was not by trying to find more power, as Porsche did (increasing its hybrid system from six to eight megajoules) but by making better use of whatever power was available.
Audi did increase its hybrid capacity from two to four megajoules, and added some displacement to the engine, but the big boost seen in 2015 is all aerodynamic: the car, in Le Mans trim, is almost as fast as the amazingly quick Porsche, yet still has enough grip to drive around the outside of any car at just about any corner.
Porsche has yet to unveil its low-drag Le Mans bodywork, but even if the car gains a bit of top end, it is tire wear which has been the car’s greatest weakness since its introduction in 2014. While the conventional wisdom has always been that speed is king at Le Mans, if Audi can shorten a sufficient number of pit stops by not changing its tires, the team could possibly gain half-a-minute every dozen laps or so for three out of four stops. if the race stays green and cars pit 27 or 28 times, this could add up to ten minutes over the 24 hours—much more than the Porsches could gain on pure pace.
The Circuit de la Sarthe is gentler on tires than Silverstone or Spa, but in a lower-downforce configuration, the Porsche’s tires would be that much more likely to slide or spin, giving the edge to Audi.
Toyota is an unknown. The team managed third and fourth at Silverstone by not getting caught up in accidents or having serious mechanical issues, but only the #1 car finished on the lead lap. At Spa the #1 car had issues some sort of electronic problems with the throttle and gearbox, which dropped the car to eighth at the finish, six laps down.
The #2 Toyota had no problems at all, and still finished fifth. The car was just slow compared to the Porsches and Audis. How the Toyotas might perform at Le Mans is a complete mystery. Possibly Toyota has special modifications planned, or maybe the team is hoping to simply outlast the competition. Considering how Audi and Porsche have been performing, that is not a smart bet.
All things considered, the smart money is on Audi at Le Mans.
The 24 Hours of Le Mans starts at 3 p.m. on Saturday, June 13, and finishes on Sunday. Tickets are available online through the LeMans.org website.
Live timing and scoring is available on the FIA-WEC site; video coverage options can also be purchased there.
