Don't forget that the JD Powers "survey" is a customer satsifaction survey, so not being happy with how much you paid for it or believing that you never have to change brake pads during the duration of a lease will cause a serious downgrade in score.
I've known many a japo car to go 100,000 miles on a set a brake pads. Of course they don't have good braking, but things like this lead to the "perception" that MBs have "problems" that are normal maintenance. If every new owner of a Benz lists "excessive brake work" as a complaint because they ahve to replace pads every 30,000 miles, down goes the rating.
Lousy gas milage when fuel costs go up is another big "complaint", as if the owner couldn't read the sticker on the window at the dealer. When it says "19 city 20 highway", don't expect more! Benz doesn't exactly make econoboxes.....
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!