You torquing to me? Are you…torquing to me?!

Audi’s 5.9-liter V-12 diesel promises 738 pound-feet of torque, or a little more than Superman would have needed had he used a car and a lonely Nevada two-lane to stop the earth’s rotation and spin us back in time. Wedge the V-12 in Audi’s R8 supercar, and we’re going a little weak in the neck.

Neither car nor engine is new, and we’ve had the opportunity to sample both. The R8 prevailed over Porsche’s vaunted 911 Turbo in a 2007 comparison test for its playful, predictable behavior, despite being slower than the Porsche. And the V-12 TDI—inspired by the diesel in Audi’s back-to-back Le Mans–winning R10 race car—made its debut at the 2007 Detroit auto show under the hood of a Q7 sport-ute, which we later drove and labeled “just mental.” We meant that in a really, really good way.

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Searching for the Outer Limits of Too Fast

Audi claims sticking the 493-hp diesel V-12 in the R8 will result in a 0-to-60-mph time of 4.2 seconds and a top speed well over the 187 mph it claims for R8s equipped with the 4.2-liter gas V-8. We say poppycock. We recorded a 0-to-60 blast of four seconds flat in our first outing with the R8, and that car was down 73 horsepower on the diesel V-12, never mind the torque deficit of 421 pound-feet. Actually, do mind it, because it’s an improvement of 133 percent. How do you say “yee-ha” in German?

All that, and Audi claims this engine meets Euro 6 emissions standards not set to go into effect until 2014.

External cues that something is amiss with this R8 include more gape to the side blades—Audi’s term for those mismatched vertical panels aft of the doors—a glass roof with a NACA duct to help feed air to the big diesel, and all-LED headlights to better replicate daytime on those long Cannonballing nights.

Originally, our sources reported that the R10 race car would not inspire Audi honchos to drop a 12-cylinder compression-ignition lump into the R8 supercar. Here’s hoping they were wrong and some serious arm-twisting has been going on at Audi.