Keeping Up Gas Mileage - at 120 mph

Fuel efficiency is serious business, even for a 650-hp racecar. That’s what Brad Kettler, technical director at Audi Sport North America, said as Audi made final preparations for two R10 prototypes to race at the American Le Mans Series’ Generac 500 last Saturday at Road America in Elkhart Lake, Wis. The cars finished second and third behind a Porsche entry fielded by racing magnate Roger Penske.

Kettler insists gas mileage is key. When the R10 pulls in for fuel, he says there’s around half a gallon left in the tank. The R10’s turbo-diesel V-12 has an inherent advantage here, as diesel fuel — in this case a special blend from Shell — is 30 percent more efficient than regular gasoline, by some estimates. That doesn’t mean the R10 sips gas: Kettler estimated each racecar would burn around 105 gallons of fuel by the end of the day. Both cars finished 96 laps of the 4.048-mile track in four hours, so that works out to around 3.7 miles per gallon — not the sort of thing you’d want on the street, but evidently good enough for the track.