I purchased this wagon with 82k on it and now it has around 117k. It has had a few repairs, but nothing truly outrageous. It drives very well, especially at high speeds on the highway. This wagon can take on 85 mph all day. I have averaged about 21 mpg, with about half highway and half city. The 4Matic AWD is truly a dream. One nice touch is the third seat. It's not habitable by adults, but my children think its a novelty to sit in a rear- facing seat. One maintenance item to watch out for: the rear window regulators WILL break, and they are about $400 to replace from the dealer. Try to find a European auto mechanic rather than always bringing it to the dealer.
Dealership is just a total rip-off, some reliability issues. Cupholders are horrendous. Many of these cars have a tendency to burn oil. Mine goes through about two quarts every five thousand miles. Fix the window regulator issue.