DETROIT – Audi AG remains high on the potential for diesel engines, including here in the U.S., but any thoughts of offering a diesel version of its exotic R8 midengine sports car appear dead.

Audi made a big splash with a diesel R8 a year ago at the 2008 North American International Auto Show, unveiling the concept in part to test consumer interest but mainly to raise awareness for modern diesel engines by wrapping one in the exotic packaging of the $100,000-plus 2-seater.

Audi has been racing successfully with a diesel-powered R8 at Le Mans since 2006, and the show car incorporated a slightly bigger displacement – 5.9L instead of 5.5L, narrower and detuned version of that engine. The concept car’s V-12 boasted 500 hp, while the racer’s diesel delivers 650 hp.

At the time, executives said Audi was “writing a new chapter in diesel technology” with the concept, and they didn’t rule out a production version of the car.

But Audi of America Inc. head Johan de Nysschen says costs and limited resources means it is unlikely a diesel R8 will hit the streets.

“Technically, of course, it is possible,” de Nysschen tells Ward’s. “(But) the R8 is low volume. And we don’t feel it is feasible for us to have so many powertrain combinations for such a low-volume car.”

Audi did up the ante on the R8 at this year’s NAIAS, unveiling a V-10 version of the car. Slated to be available in Germany in the second-quarter, it features a 5.2L, 525-hp V-10, marking a huge step up from the base car’s 4.2L 420-hp V-8.

The V-10 also offers 78 lb.-ft. (106 Nm) more torque at 391 lb.-ft. (530 Nm) and will take the car from a standstill to 62 mph (100 km/h) in just 3.9 seconds, Audi says.

Prices will start at €142,400 ($187,147) in Germany.