I was surprised to see the write up a couple of months ago in Consumer Reports about new MB's; they pretty much tell you not to buy them based on the experience of a few thousand owners (number is no clear).
Today the LA Times makes reference to it:

"But maybe not everything. A cautionary note for would-be buyers: Strange things seem to be happening, quality-wise, at Mercedes. Consumer Reports said in its latest auto issue that the C-Class was "well below average" in reliability as reported by owner/subscribers in the magazine's annual survey. (The incredibly expensive S-Class line gets the same crummy rating.)

There's more: Mercedes fell to below average in J.D. Power's last survey of dependability over five years, which was issued in November. The carmaker was below average in customer satisfaction with servicing, according to another Power survey. Mercedes did, however, come in just above average in another more recent Power survey, measuring quality and customer satisfaction in the first three months of ownership. The average number of complaints increased from a year earlier."

It seems that one should look at 10 year old models.

Juan.