2011 downtown 300i, same problem, at first I thought it was old age , but what the hell Im only 79 at that time, cant be me, so I brought it in to a moter cycle upholsterer, and he did a nice job on the cover but he put in regular foam, better but not good, so I took it appart, and installed rebond foam, 4 inches thick, sliced a slant in it so I did not slide forward any more, tact it together again and been happy ever since, longest day so far is 550 miles, and was good for more,