How about a Bentley Continental GT CleanTDI?

During the past two Detroit Auto Shows, Audi has shown concept versions of the Q7 SUV and the R8 sports car powered by a new 6.0L diesel V-12. While the Germans have equivocated on whether the V-12 Q7 would ever get built, they stated clearly that they had no production plans for the R8 TDI. Perhaps a better home could be found within the VW Group at the Bentley brand. With upcoming European CO₂ limits, Bentley will have to do something to reduce fuel consumption. The V-12 used in the concepts apparently won't fit in the engine compartment of current Bentleys; however, such an engine would be ideally suited to the character of the brand. These big grand touring cars don't need screaming, high-revving engines but the huge torque of a big diesel would be a perfect match and could push mileage up into at least the mid-twenties. It would be no surprise at all to see next-generation Bentleys re-engineered around this engine.

[Source: PistonHeads]