I have a 2010 Mercedes GLK with 17,000 miles.
I just had to get the transmission replaced.
At first they told me it was the wheel bearings.
Then the next day they called me and said it was not the wheel bearings but instead they needed to replace the transmission.
I went online and saw other owners with the same problem! I was thinking about buying the car after my lease is up but I just changed my mind.
Not sure what other problems are lurking.
I also have a 2010 GLK with almost 33k miles and 6 more months of warranty left.
My story is the same.
First they replaced the bearing.
When I returned with the same problem (high pitch noise starts over 40 miles per hour) they asked me to drive with a tech on board.
He did not say much but I can see from his reactions that he knew that it was a major problem.
They kept the car 2 more days.
To me it meant MB rep had to come over and make the expensive decision.
I was going away for a week so did not mind them to keep the car.
When I returned several warranty fixes including a brand new transmission were completed.
The dealer service personnel were very responsive and helpful.
Only time will show if I have a lemon.
Luckly I had purchesed mechanical breakdown ins up to 100k miles.