I got the old thing up to 70 today for the first time , at first I thought I had left a window open as there was a repeating "wump wump wump" noise , you could actually feel it as well, not horrendous just slight, does not happen at 68 MPH just at 70 and does seem to be at the rear. Next thought was tyres , I checked them and they are all good and at right pressure. Local Indy jag specialist at a loss , they have never seen this before. An Jag owning acquaintance suggested that this is caused by airflow over the tail gate lifting the tailgate because the seal is worn . Don't fancy this idea much as the seal looks in good nick and there is no discernible movement in the tailgate once it closed. Next move is to swap the wheels front to back and see if it tranfsers the noise to the front , but clutching at straws , i think
Any one seen this kind thing before ???