I have been a avid Mercedes roadster owner for several years now. I’ve have an SLK350 for the past three years. But getting older and my sciatica acting up after an hour or so driving the SLK, I decided to purchase an SL550. It’s a 2011, black on black. Love the car, so much different. I noticed a slight (almost annoying) vibration sounding almost like when you roll down aback window in a car and there is a thumping, reverberating kind of vibration. I put my hand on the roof next to the back window and it is vibrating. This seems to happen from about 40 mph all the way up. There is no vibration in the steering or when braking. The only thing i can think of is having all the tires rebalanced, but really don’t think that’s the issue. Anyone have a similar experience? Thanks.