I believe that the common ownership trend is that new MB cars are bought by relatively wealthy owners who have their cars serviced by the dealer. The owners tend to be older who don’t abuse the cars. They tend to be kept in garages.
I don’t think you can make a blanket statement like that across the model range.
I very much believe that most C-class buyers (and the new A-class) are not relatively wealthy or old and their purchase is very much a “my first Mercedes” experience. And Mercedes sells a boatload of C-class cars. By contrast: after I bought a R230 SL55 I was invited by Mercedes to a focus group in San Diego where they told us that the typical SL buyer was in his mid-fifties, bought the SL as a 3rd or 4th car and had an average income of $400,000 (none of which described me). So that group of owners more closely fits the demographic of your statement.
Also, far more people lease than buy in the luxury car market, and your post doesn’t consider this trend. The ownership experience is a different one when you lease instead of buy and off-lease cars tend to be in better shape (or at least that’s the common perception). Off-lease cars also tend to hit the market as "2nd-owner" cars before cars that were purchased.
At some point the maintenance costs begin to burden the second owner & he sells the car.
I agree, but this is just an unhappy coincidence not restricted to Mercedes, in that all cars typically require more significant maintenance in the years/mileage period that coincide with “second-ownership” and out-of-warranty repairs on any German import are going to be expensive.
I like to watch auto auctions on TV. I find it interesting that a late 60s fixed-up generic Chevrolet (for instance) might sell for over $20k and then a 12 year old MB SL600 might sell for $14k. The Chevy is seen as a “collector car”. The MB is just a used car. There is little doubt about what is the better car.
I don’t know about qualifying as a “better” car, but I can tell you that 12 yr. old SL600 would be very expensive to maintain and run. My overall opinion on Merc reliability is that the engine and trannies are solid, but the rest is a crapshoot. The SL600 in question here would have serious and extremely expensive ABC suspension components that would need to be replaced (if not yet done) and very suspect electronics across the board.
Oil changes would require about 11 quarts of synthetic, brake rotors and pads would be about $1000 per axle and you’d be paying higher insurance premiums than just about any other car on the road. You'd also get horrific fuel economy. People who shop at televised auctions are typically well-informed, and the market demand for such a car is probably fairly reflected in the price.
In summary, I believe that if one can research a used MB and is willing to maintain, diagnose & repair much of the car themselves, a used MB can be a real value.
I think that the effect of the Chrysler years on Mercedes is a real-thing, that seriously created reliability issues for models that were designed or built in that period (late nineties - mid 00s) from which Mercedes has only recently recovered.
Their reliability ratings tanked for a long while and my first-hand experience with a Merc from that period are consistent with those ratings.
An example that speaks to the design approach in that period: is that the main reason that the Merc 8-cylinder had only 3 valves per cylinder in the “500” years was Chrysler cost-cutting on the drawing board. 302 HP and 339 ft/lbs is pretty meagre from an engine displacing 5 liters. Post-Chrysler, the “550” engines went to 8 cylinder/32 v. with a significant boost in power from the same displacement.
I’ve owned new Mercedes, BMW and Porsches in the last ten years and I would rank them Porsche – BMW – Mercedes for reliability and perceived quality. I do think that Merc is turning things around and I’m very pleased with the quality of my R172, although frankly, reliability in my limited period of ownership has been less than stellar.