Are you implicating that the Mercedes factory would send an automobile out of their delivery with different wheel sizes fitted??
I do not think any (serious) car manufacturer would do such a blunder.
I see Hans, that you removed nefarious references to Ford and GM!
In my 20+ years of 2 or more Ford products a year being driven--and many with lots of miles (my daily driver Ford just turned 30,000 miles) we have never had a problem with any of them. In fact they are, as a lot, infinitely more reliable than my home appliances! In that run of Fords were one Volvo and one Jaguar, both of which did have issues. My beloved aunt, from which my Pagoda came, is driving a 2012 SLK350. With light use (you know, the little old lady thing?) of 4,500 miles over 3 years, a slight ticking sound coming from the engine bay was recently fixed at the dealer. One set of pistons, one set of con rods, new heads, (all under warranty of course) and she was good to go. Essentially a full engine rebuild on a what amounts to a new car. Go figure. "I do not think any (serious) car manufacturer would do such a blunder" but apparently at least one bad engine got out of the factory...
Bottom line? I think anything is possible from any manufacturer. But...
…if I'm handing out prizes for the best guess here, it's Cees. And yes, Alfred, the rim will be replaced…with a 6".