I have a 2003 BMW 330i sedan that recently hit 140,000 miles -- thanks to Joel, Melissa, Greg, and everyone else at Arizona Imports/Bill's Bimmers. Joel goes out of his way to make sure customers are valued, and Melissa is a pleasure to deal with.
I used to think buying a used car was a crapshoot, but with Arizona Imports I'm looking at previously owned M3 coupes because I know they'll take care of it for me.
Update (2010-07-11): My 330i is now at 164,000 miles and still going strong!