a Mercedes, because you already have the discount. If it's still under warranty, then you'll do okay, as maintenance, when they do occur for the MB, BMW or other German cars is not cheap.
If I wanted the best maintenance for a used car, then I'd go Toyota or Honda. Not the prestige, but certainly more cost effective, and usually reliable.
Archaea,from the deep dark blue leagues beneath the Sea. Cool under pressure yet a microbe in the sun.