OP was obviously joking since there is absolutely no chance whatesoever of a performance diesel being sold in the US.
However, I agree that a F3x "M350d" N57S model would be pretty cool. I doubt that they will do it since the "50d" model designation seems pretty unlikely for a sub-5 at this time. Although I suppose they could use a detuned version in an "M340d" or "335d".
A gen-u-ine BMW eff-eight-zero with them tandem clutches in the transmission and that dad gum sun roof on the top-a da cawr.