Audi R18s Were Forced to Cut Weight to Stay Competitive

AudiAudiGermany, 1909 > present83 models
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is admitting something rather interesting about its R18 E-tron QuattroAudi R18 e-tron quattroGermany, 2012 > present8 photos
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that might explain why it came in second to its sibling the R18 UltraAudi R18 ultraGermany, 2012 > present11 photos
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at the 6 Hours of Spa and might give us an idea of what will happen at the 24 Hours of Le Mans.

Audi Motorsport says that it knew the hybrid car would weigh over the 900kg weight minimum for the LMP1 class when it started developing the car. Last year's R18 was already below this magic number, and the addition of the hybrid system and all of its components brought the R18 E-tron Quattro's weight up to around 990kg. It forced the engineers to come up with novel ways to bring weight back down to as close to 900kg as possible. 

Audi went bit by bit through the car. The carbon fiber gas pedal got a shave reducing a few grams, but one of the biggest changes came in the transmission. It created a carbon fiber transmission housing that Audi Motorsport considers the largest technical leap on the car. While this technology is already used in Formula 1, those cars have a minimum weight of 640kg. A carbon fiber transmission case in an LMP car needs to take more weight and be able to do so for 24 hours. 

Even the bodies of the cars are engineered in such a way that there is only one spot that the drivers can step on to get into or out of the car without harming it. 

"The R18 ultra has provided the basis that made it possible to implement the E-tron Quattro in the first place. If we hadn’t managed to implement the weight difference between the 2011 R18 TDI and the 2012 R18 ultra there would have been no chance for a competitive hybrid," said Head of Audi Motorsport Dr. Wolfgang Ullrich.

All of those changes to the R18 E-tron Quattro were then moved over to the R18 Ultra, which also gets the aerodynamic changes from the Quattro. That means that the R18, which was so competitive last year, has been lightened even more. While the car will have to carry ballast to get it up to 900kg, the engineers can place it anywhere they want for optimum balance. Audi basically created an ultra-light version of last year's Le Mans-winning car without really even trying. 

If we look at the performance from last week's 6 Hours of Spa, this might explain why the R18 Ultra was so competitive in the dry laps and won the race. As long as there is grip, it seems like the R18 Ultra is a faster car thanks to its better weight distribution.