Audi seems to have no trouble winning LeMans with its ultra-sophisticated R18 models in the last decade — but has struggled mightily trying to translate racing tech to the road.

Even today, there is no clear link between Audi racing glory and the cars sold by Audi dealerships. Sure, there is anecdotal evidence hat motorsport success has fueled Audi’s continued sales rise — but it is a tenuous link.

Upon the arrival of Audis’ first supercar, the R8, this finally looked set to change. At last — a way to show how LeMans racing improves the breed in general!

The method was to use a race-ready diesel V12 engine in the R8 road car, and led to this 500-horsepower R8 TDI concept in silver, plus the R8 TDI LeMans in red orange.

Adapting the R8 chassis to accept the huge V12 TDI engine was no small task: there are rumors that the entire rear floorplan and suspension are redesigned in carbon-fiber. That large expense may explain why the R8 team did not put this engine into production. At the time, they were balancing at least two other must-haves:

— making time for the a gasoline V10 for the top-dog R8

— fitting an all-new DSG into the mid-engine package to replace Lamborghini’s dreaded E-Gear automated manual

— exploring an all-electric drivetrain, as well

The rumor is that the next-gen R8 may, indeed, use a TDI engine at some point in its life. It may even incorporate some of the hybrid assistance seen in the R18 Ultra or R18 Quattro.

But the biggest hurdle remains: what is the market for a heavy and low-revving supercar? The diesel engine will add at least 300-pounds to the chassis, while its sprint pace may struggle to beat the base R8 V8.

Until these hurdles can be overcome, the idea of a supercar R8 with a LeMans-style diesel engine (and in-gear torque!) will remain just a showcar fantasy.

2009 Audi R8 TDI V12