ive had my car for almost 2 years now and here are some problems that ive come across.
problem 1
when going in reverse like to back out of a parking space, there would be a loud clunk when i would apply my brakes after backing out.
this was caused by time. over time the control arm bushings would become loose.
i had the control arm bushings replaced (not cheap - many labor hours) and the problem was solved. the ride quality of the car also improved
problem 2
as some others have stated, i have had sticky speedometer and tachometer gagues.
all of the sticky gagues were caused by a breakdown of the black paint on the needles which becomes sticky.
the solution is to clean off the sticky residue from the needles.
http://www.benzworld.org/forums/w202-c-class/1326591-w202-cluster-fix-read.html
http://www.benzworld.org/forums/w202-c-class/1350908-replacing-dash-bulbs-c280.html (this one gives better details on removing the instrument cluster)
problem 3
i had an intermitten turn signal issue, and in the rain when using my wipers i noticed that in the first postion of the wipers, it would work intermittently. then one morning i noticed my rear window defroster wasnt working.
these 3 issues were all caused by the same relay. it was a multifuction relay which controlled all of these functions.
i purchased a new one from autohauz and replaced it. it is located right above the fuse box with a bunch of other relays in the top right of engine compartment.
problem 4
i had a check engine light come on, and was told is was from one of two components, the transmission wasnt holding vacuum and it was either the upshift delay switchover valve or the kickdown solenoid.
i replaced the upshift delay switchover valve and the check engine light came back on, then replaced the solenoid. which solved the problem, however ever since all of this my transmission has not been shifting correctly. i have been trying to adjust my transmission to get it perfect, and have gotten it alot better, but some of the shifts are still a little too firm.
hope this information helps someone out!