Ok well heres the whole story. My brand new 2k 540 with 9k miles was in the shop for 2days because of a rear diff. problem. What the problem was is that when I would drive it would be fine, but when I started to coast it would make a ticking sound. It was VERY loud! so I took it in...replaced the diff...all is well. Now not even 3 weeks later, Same thing! exact same thing happens! I have no idea what it is. I just called BMW roadside assistance to have them tow the car to the dealer cause the car is un-drivable. Has anyone had this problem or known anyone that has? Im very poed right now with BMW...Thank you for your time.