In reply to maybe_si:
In the 2000's, my brother used to work for a large, limo hire company which had dozens of Mercs, almost exclusively S-class. He said with regular maintenance, they were all bombproof and would have no hesitation in buying a used Merc. (with FSH of course).
I'm thinking about switching to an E-class estate next time round. I've toyed with the idea of a C-class but they feel a bit small and I like to be comfortable during longer drives.
Edit: should have added that he was responsible for arranging all servicing etc and that it was surprisingly affordable when they used their non-dealer specialist to do the work. Most of their cars did 300-400k miles and looked brand new, even the older ones with private plates.
Post edited at 12:21