Keep in mind, in the world of INTERNET, you will be hard to find an honest / unbiased answer to questions like that... especially in a Mercedes Forum.
Mercedes forums says AUdi and BMW are costly.
Go to BMW forum, roadfly, and BMW's are maintainance free compared to "expensive to maintain MB"
go to Yugo forum, "these are the best cars on the road, no one understands them"
go to Ford forum...... well, they're hopeless, just an Ameican car, lol
Get my point? You will have to go to an Audi forum and search how busy their Tech section is ...... Audi is a division of VW... I have had a 97 and a 99 VW with little problems.... I know in the past, past, past AUdi's were junk... newer years, I don't know..
Just as an FYI, when I bought my 95 E320 recently, I entertained A4's, but got scared off when I read of some expensive tranny problems. I did NOT probe further to find out what years / issues they had. just dropped the choice...
Good luck