I can't find a lot of fault or error in CR's ratings. I've used them to make purchases MAINLY because they don't accept advertising dollars from anyone, so the reports shouldn't be slanted in favor of thier biggest advertisers (since they have none).
In MY experience, the CR ratings are pretty accurate / reliable.

As for Mercedes, I've only driven one. That's all I needed to know that an MB wasn't MY type of car. Sounded like a tractor and felt like a boat.
With Mercedes as the parent company of DCX, it seems to me that the inmates are in charge of the asylum.