I know the service manager for Mercedes at the dealer closest to my home, and he told me (off the record, of course!) he had a few customers who had traded in their 190E's for a then new C class and then came back a few days/weeks later only to want their old 190E's back because of the lack of quality in the C.
MB & BMW used to build great cars (635i/M6/300E coupe, anyone?) until Acura/Lexus/Infiniti came along with comparable products at more than comparable prices. In a nutshell, what used to happen, was that the engineers at MB/BMW would build the car, then hand it over to the accountants to put a price on it. Now, it's the bean counters who tell the engineers the price point to build the car. This has resulted in a lot of corners being cut. It's all Acura/Lexus/Infiniti's fault! Lexus has become the marque most feared by the big three German makers, with Acura a distant second. In my opinion, Infiniti is a big failure (sadly), with the G35 their saviour for now. I wish Lexus cars had an anologue clock like Infiniti, though...very classy.