I'm not sure how reliable this site is but in general, it is accepted that most luxury German cars have reoccurring issues. The reason why I say "accepted" is because in most cases, they are pushing cutting edge technology and with so many parts, something is going to give.
I do not know common Mercedes issues but with BMW SUVs the most common issues are plastic parts near gaskets (leaks), electrical systems, and ventilation (especially in X3).
Of coarse there are exceptions and not all cars are created equal but this seems to be the consensus year after year.
Look at the bottom of the doors of almost any Mercedes B-Class produced before 2009 and you will see brown corrosion traces. My B-Class (bought new in 2005) was literally falling apart from corrosion. They had massive quality problems in the early 2000s, with the B- and C-Class.
I know this is my personal experience, but I will never be able to purchase any Mercedes car ever again.
That's bad luck! But... if you'll never buy from a manufacturer because one of their models had a corrosion issue or drivetrain issue you'd never be able to buy a car ever again?
It's one thing to have "a corrosion or drive-train issue" that affects a model or series of models built with that design. It's another to repeatedly have the same issue, repeatedly say it's fixed and then have it turn out to be not fixed. Toyota light truck frames, Nissan CVTs and arguably Honda A/C systems are the quintessential examples of this (though in Honda and Nissan's defense, they never claimed to have ever done anything about it).
I'm not gonna comment on the Mercedes because while they definitely have earned their reputation for being expensive in old age I'm not familiar enough with them to pass a value judgement.
I'm not sure how reliable this site is but in general, it is accepted that most luxury German cars have reoccurring issues. The reason why I say "accepted" is because in most cases, they are pushing cutting edge technology and with so many parts, something is going to give.
I do not know common Mercedes issues but with BMW SUVs the most common issues are plastic parts near gaskets (leaks), electrical systems, and ventilation (especially in X3).
Of coarse there are exceptions and not all cars are created equal but this seems to be the consensus year after year.