your suspension has failed due to the lines or the air bags in the rear. I have also experienced full dropping upon the failure of the front strut. This is a common dangerous problem for which I am searching for individuals who have experienced and/or been injured due to a sudden movement or turn of the car while driving. I am an attorney and it surprised me to see 9 cars identical to mine at an independent mechanic shop with the same problem.
I have had same issue both front and rear on my 2004 E500 4matic seems to be a serious problem with this car I actually thought I hit something in road car dropped all the way insurance took care of it first time can be a very expensive repair issue
I had the same issues with my 2005 E500. I found out that my relay had come lose causing the vehicle to sit low and not rise. once I took it out and put it back in, my car immediatley came up. The pumps were working and it has worked fine every since.