the squeeky suspension might not be from the suspension. i have a similar problem on my t-reg and so does my gf with her slk. when we went to the dealership, the technician at mb said that the squeek might be coming from the parking brake. and sure enough, when the parking brake wasn't pulled the squeek would go away. but i konw how you feel, luxury cars (especially german luxury cars) shouldn't make sounds that wouldn't even be common place in todays korean cars.

my suggestion is to get a new car. one that leaks water through the door can be a bit annoying (something i experienced while driving an old chevy monte carlo).