I never understood when people say dont germans as these are expensive to maintain! that goes for almost every car, sure parts availblity will be an issue where you live!
apart from that from personal ownership experience of BMW(318i, 330CC, X5), AUDI(A4, A6), Mercedes(CLK, E-Class, A-Class) (though i would rate merc third in reliability) they only need normal service a year plus any wear and tear to brake pads and disks. all can be done at good garage or by yourself if you are fine with it.
I dont buy brand new cars because of depreciation of first 2 years are almost 40% so buy only a few years used cars these all served me well, didnt give my any major trouble. I do yearly service at their dealership to keep the service history sake, rest i do myself or any indy.
If you know what you buying then it helps as buying blindly may just be a lottery! A good maintained car will give you reliable drive and pleasure.