I have the stone leather interior in my E320 and my pants belt leaves, for lack of a better term, a stain across the seat back at the belt level. This has not only happened my E320, but other vehicles with light colored leather seats, I have owned. In the past I have tried a number of leather cleaners, but none of them will eliminate the stain, or even partially remove it.

Does anyone have any suggestions? Zymol cleaner doesn't work.

 

I have the same problem with my daily driver, 2000 Honda Acura 3.2 TL with tan interior. I tried everything, Meguire’s leather cleaner, Murphy’s Oil Soap, saddle soap, variety of household cleaners, OxyClean, Dawn, special leather cleaner bought at the auto parts store, Magic Wand, etc. No luck.

I didn’t damage the leather, though, and my work on it did lighten the stain. After 3 years and 30K miles, the stain has faded quite a bit. Appears that the stain isn’t as colorfast as the original leather color. I bought a cloth belt for the times that I don’t wear a jacket. Else, I put a towel on the seat back (Hey, its just me in the car!).

My 2005 SLK Diamond Silver has blue leather. Black interior is so dreary.

 

OK i'm going to give you this tip but with a heavy
WARNING!
This stuff is AMAZING
but dang it, if it's not wickedly strong!

Mr. Cleans- Miracle Eraser
Buy it at Home Depot

Afterwards; renourish the leather

Good Luck!