 I really like my 2004 A4 but it has been in the shop too many times.  It had problems with the turbo charger at about 37k miles, then a leaking oil gasket at 45k, ignition coils replaced at 48k and the entire 2nd cylinder head was replaced shortly after that.  Luckily this was done under warranty but I'm thinking of selling it now before anything else can go wrong.