Seems like your mind is already set on a Mercedes, and if that's really the case then no amount of persuation could possibly convince you otherwise.
But let me put it simply and as delicately as I can:
Buying a 20 year old Mercedes is the WORST decision one can possibly make while purchasing a used car. It just doesn't make any sense unless the car has collectors status or perhaps possess some sentimental value.
Don't listen to me, friend. Go over to some international forum dedicated to Mercedes Benz and ask them. I'm sure they'll be able to answer your each and every query and then you'll see what I mean.
But generally speaking, a two decade old Mercedes is a recipe for disaster.
Best of luck.