I'm not proud to have to post this but over the past few years I've noticed many MB cars here in the Northeast US with rust which I consider unacceptable. The W202, 203, 210 and 220 seem to be particularly rust prone.
I really love Mercedes cars as I was practically born into them. I've driven nothing else all my life except for a BMW during my college years. I've put over 500,000 miles on Mercedes automobiles. I'm particularly proud of an 800,000 mile 220D which I successfully drove cross country and back with no breakdowns. I'm also proud of a 450SEL which was driven to 330,000 miles with absolutely no engine work except for a timing chain replacement. I still have a 1971 220 bought new by my parents. This car is in pristine shape.
I am still the proud owner of mostly older cars: 1958 300d, 1963 220SEb coupe, 1971 220, 1971 280SL, 1973 220D, 1982 240D and a 2005 G500. I am however very hesitant to purchase anything new or newer from Mercedes based upon what I consider a pretty bad rust track record. It's too early to tell what the W204, 212, 221 etc models will do and honestly I'm not sure I want to find out. I would really like to continue to buy Mercedes cars but some reassurance would be necessary. Where I would get the reassurance I don't know!!
Here are some pictures I've taken over the past few months to illustrate my point. These are not what I would consider fluke occurrences as I've seen many, many more such cars which I did not photograph. These cars have rust everywhere - not just one isolated panel which could be attributed to poorly done bodywork. All these photos were taken in Massachusetts.