So, the engineering that goes into M-B cars is great. You repair whatever and that repaired thing is not going to fail for a long time. But, the entire car has various things that will break down over time, brakes, suspension, engine, transmission, etc. If you repair an engine seal, its going to last for tens of thousand of miles, but that doesn't prevent other things like the alternator, air conditioner, motor mounts, brakes from needing repair or replacement.
Compare the cost of a Mercedes-Benz motor mount to a Mazda one. It's like double the cost. Does the same thing, it holds the motor up and absorbs engine vibration.
from my experience bmws are terrible cars, they over heat etc
Benz drive forever, but thats only S class, I don't know about those other cars
and the S class is the only benz considered luxury