From the area you have highlighted I would suggest seat belt wear.

My W126 420 SE has significant wear in that area (anyone know where to get grey leather dye?).

Although my car came from Hong Kong, you see a lot of wear in that area here in Australia.

We have had mandatory seat belt laws since the 70's and so did Hong Kong.

Other areas of damage I would imagine are due to the portly driver.

Cheers

__________________
1988 W126 420 SE

beware of fundamentalists!