I have no clue?
 

Can somebody please tell me, " why do i see a fog looking stain in the back window of some of our cars (MB)?

Will it wipe off or permanent?
Gilly

The older cars have a type of "shatterproof" glass. It's actually two pieces of glass with a sort of "saran wrap" type of film sandwiched between the two. After time, moisture will creep up and form the fog effect you're talking about. I don't know of any way to get rid of it short of replacing the glass.

PowerPig you are correct. My '80 300SD W116 windsheild had a little of this whitish discoloration around the edges. I thought someone had used a can of spraypaint near it. When I brought the car in to have the windsheild and rear window gaskets replaced they told that it is actually the glass delaminating. Typical with age. They couldn't promise not to break the glass when they removed it and would not accept the responsibility for breakage. Guess what - I had to get a new windshield but the rear window came out and went back in OK.

It's the beginning of window delamination on these, common with some of the older models. Only cure I know of is to replace the glass.