Are there any plans to bring Diesel powere Audis to the united states? they get better mileage and perform very well and I dont understand how the audi A1 got 50mpg in europe but didn't pass American emissions standards to come to the US and that doesn't make sense to me at all.  

Amen, brother. Even the huge a8L diesel will get 40 mpg if you drive it gingerly enough. but for real world count on 35-32. thats still preety darn good.  

I dont know when a diesel audi will come to the us but there are only 2 models I can think of that you could make diesel if you wanted to... the TT (using the 1.9TDI from a Jetta/Golf MKIV) or the A4 (using the Passat engine).. food for thought... I dismantle VW/AUDI cars and that was the first thing that came to mind...  

Just to clarify - I am guessing you are referring to engine swaps with commonly available parts in USA/Canada.

In Europe, Audi overs V6, V8 and V12 diesels of approximately 3, 4 and 6 litres displacement.

VW fills in with a 5 cylinder in-line (2½ l) and a V10 (5 l), in addition to the 1.9/2 4 cylinder.