Hi, I have a 2006 E500 SW 4Matic with about 130,000 miles. I have also suffered from this problem...and when I changed the fluid, viola, it went away. Then about a year later, it came back and again, changing the fluid made it go away. The reason I say this is that someone spoke of glycol getting into the ATF via the radiator.... targatime (and others) maybe we should get our radiators checked... I also have another problem, a "knock" coming from underneath the center of the car. Maxes out at 35-40 MPH, although occasionally it happens under acceleration. More of a noise than a vibration, like the exhaust hitting against the crossmember (no, it's not that, I checked). I will check the flex discs and center bearing (if any). Any other suggestions?