I don't think it is as much a "peeling" problem for most of us, as a vulnerability to being knocked off or scratched when bumped. Because the SLK comes with several interior color packages in which the hard plastic parts are "painted" to match the upholstery, ALL of the molded parts are molded of a black plastic material, which appears to be that of the upper dashtop material, then painted with either a charcoal grey (for the single color interiors) or a light cream, red, or blue, for the more colorful versions. Like most plastics, they don't take and hold (politically correct in Germany) mostly water based paint too well, so that if the paint is gouged or abraded, the black plastic shows through. The light colors reveal this worst, but you can also see where the charcoal grey is knocked off, just not as badly.
We would all have been better served by the use of solidly colored plastics, as most cars have these days, or an interior style that did not require painted plastics to match the rest of the interior, such as leather covered consoles and 'bump" pads in vulnerable locations.
The latest version of the R-171 seems to have a more durable choice of interior materials for the similar parts (although the first R-171s used a rather "creepy" material for the dash.) Why they seem to have lost their memory of the durable plastics used back in the '70s is a mystery.