Diesel's ascendance in the U.S. is a story that's been slow to develop momentum. For years, we've been hearing they're coming--and many are already here--but they're still just not a major factor in the marketplace. Mass buying preferences aside, however, there are some brilliant examples out there, and Audi's U.K. arm has just announced what looks to be another: a twin-turbo 3.0-liter V-6 BiTDI engine rated at 308 horsepower and 480 pound-feet of torque.

Those are solid figures, to be sure. BMW's 3.0-liter six-cylinder turbodiesel yields engaging performance and surprising fuel economy (23/36 mpg) in the 335d, but generates a comparably less exciting 265 horsepower and 425 pound-feet of torque. Audi's new 3.0 BiTDI cranks the output up by about 15 percent--and it may be coming to the U.S.

Intended for the A6 sedan and Avant, A7, and A6 Allroad, the new engine (which you can hear here) is also a potential candidate for the Q7, which already has a diesel variant in the U.S. And if Audi goes to the expense of having the engine certified for U.S. sale, it could wind up in the A6 and A7 range--and even the A8--as well. According Quattroworld, Audi insiders are planning exactly that, with the Q7 first to bat in early 2013.

While that's purely speculative, as Audi hasn't made any indications that the new 3.0 BiTDI will be sold in the U.S., it would mean a huge boon to lovers of high efficiency luxury/performance cars.

Of course, the new Audi diesel could end up being another Europe-only special we'll be left envying from afar, like BMW's M Performance tri-turbo diesels.