So, since I bought my 2001 S 55 I noticed this vibration inside the car, no shaking, just vibration. I asked my cousin to drive it he couldn't feel it. I had to change the tires recently cause they needed to be replaced and was hoping it will take care of the problem, it didn't. I rebalanced it, aligned it, new front rotors and brakes, rear brakes. Car has 70K miles, very clean. Today I asked MB dealer to check it out, he said the rear trans mount need replacement. No other mechanic said anything about it when I asked them to check the mounts. How do I know it will take care of the problem? He wants $240 for parts and labor. I have an appointment next monday. To be honest I feel it between 30-45 mph, especially when I kick down for example from 3rd to 2nd or from 4th to 3rd, most noticeable.