I have a 2001 E-430, whcih has this rocking or "click" in the driver's seat. Local dealer says it is an interior trim problem and not covered under my extended warranty. It obviously is a defect in workmanship and should be covered by an overall "fix" by Mercedes. My car is less than 3 years old, but now has 93,000 miles due to a long commute each day. The click showed up around 50,000 miles-still no satisfaction from MB. If anyone has had the problem fixed- I would like to know.