Anyone would have thought that such an amazing run of victories would have changed minds about the suitability of diesel engines as performance powertrains. If winning on the ultimate Sunday doesn’t trigger a case for a diesel supercar, what will?
Perhaps production oil-burning engines were still not good enough. Not refined enough, too slow to rev, too quick to lose boost and unlikely to tempt the sort of enthusiast who buys an Audi R8.
Intriguingly, the winning R18 e-tron quattro of the latest couple of years used electric motors on the front axle, which helped fix one of the problems with traditional diesel engines: the rapid loss of turbocharger boost – and torque - as the driver lifts off.
Of course, that could have been replicated on a road car using an electrically driven rear axle (Audi has long-promised an electric quattro system for road cars), which could ‘fill in’ the gaps in the diesel engine’s torque curve.
All that said, having driven the Audi RS5 with the new ‘e-boost’ V6 diesel engine, I think it is a near dead cert that we will see a diesel-powered version of the next-generation Audi R8.
The new-generation lightweight unit uses typical two-stage turbocharging. The smaller of the two turbos is lighter and easier to spin up, and is intended to give the engine more grunt at lower engine speeds. The bigger turbo takes over at higher speeds.
Audi engineers have added a quite simple electrically powered blower to the engine’s induction system, which, at very low engine speeds, forces air into the induction system, spinning the smaller turbo into life.
The e-booster is also intended to keep the engine on the boil on, say, twisty back roads. Under braking for a corner it also slows the engine and bleeds off boost. This results in slower acceleration out of the same corner while the engine spins up enough to get the turbos back on boost.
This is where the electric front axle helped on the R18 e-tron racing car, although it was restricted to operating at speeds above 75mph by the Le Mans regulations.
Driving the RS5 prototype last month was a genuine revelation. The new engine offers an absolute wall of torque, pulls amazingly well out of corners and the exhaust system gives it an artificial sound track good enough to throw the most finely tuned ear.
When I suggested to the engineering boss that Audi now had a diesel drivetrain good enough for the upcoming next-gen R8. He was gloriously, hand-wavingly non-committal. So I can’t see it not happening.
With the new R8 due next year, there’s only one way to successfully launch the idea – Audi’s diesel race car needs to win again this Sunday.