87 300E with 131K. At 60mph and up, there is a resonant vibration that I can feel and hear even though its subtle. As speed increases, so does the frequency of the vibration/noise, although not much; i.e. at 80 mph it's a little more frequent than at 60mph. I've talked to two other 300E owners in my area and they have a similar problem, with varying degrees of intensity. Mine is rythmic and I can hear it more than feel it, although it's gotten stronger in the past two weeks. Any diagnostic suggestions would be greatly appreciated.