One problem related to engine has been reported for the 2006 Mercedes Benz R350. The most recently reported issues are listed below.
My 2006 Mercedes Benz R350 was diagnosed with a counter balance shaft/gear problem. It has 85000 miles. . . Which doesn't seem like a lot for a car that is 5 years old and supposed to last forever. Plus I have maintained the car with oil changes, tires, etc and am the original owner. I see on line that there is a class action suit pending . I believe a $5000 repair is way too much and the company should take responsibility.