I also have a 2005 E53 3.0d, again with steel front springs, and air on the rear. The car also has the 19" wheels and had done about 120000 miles on it like Ben's. I have owned the car for almost ten years now and noticed that the ride has recently deteriorated considerably for no apparent reason, and nothing whatsoever has been altered. If the car had always been like this I, like Ben, would be thinking of getting rid of it. Greydog's interesting and knowledgeable post covers many things but something has happened to my car only over the last few weeks. The only thing that comes to mind is that something has been damaged or affected since I have had to drive down an horrendously bad, potholed farm lane a number of times recently, on which I probably didn't exceed walking pace, if indeed I went that fast.
I am going to put the car over an inspection pit in the next day or so, just in case anything is visible or obvious. Apart from that, I would certainly appreciate any help at all with this issue.
John
