Let me get this straight....You said you live hours from the nearest Audi dealer and you are considering buying a used Audi? Might I recommend the 2.7tt A6 with about 100k on the clock.
Good luck....If you ever need to replace the two turbos...you will need it (or about 6-8 grand if you have a dealer do it). God help you when a front CV joint goes bad also and just go ahead and order a full set of front suspension arms as they will all eventually take a crap (Have fun removing the upper arm retaining bolt). Just hope and pray that the steering rack never takes a crap on you..... I am not sure, but I think they were installed prior to welding the body together around it.
My A6 2.7 tt was very quick and nice to drive but it was lucky to ever get close to 20mpg.