I thought you all would be interested in a short story of mine:
I had a 1986 Celica GTS and I decided to change the cloth seats with Black vinyl seat covers from JC Whitney. After spending about $200 (it also took them a while to find the exact model seats--I hat to take photos of my seats and mail them--took about 3 weeks until they figured out what kind of seats I had).
Anyway, I spent several hours removing the seats and fitting the black vinyl. They looked GREAT! They felt good and I loved the dark black color.
Then I noticed a slimy film covering the inside windows!
After much research I found the culprit:
The windows got slimy because of the off-gassing of the phthalate plasticizers contained in the vinyl seatcovers!
Phthalates are added to hard plastics to make them soft and flexible---that is what vinyl is.
The off gassing of the phtalates caused an greasy oily film to appear on the inside windshield and all the other inside glass. I remember it took HOURS to remove it, and it JUST CAME BACK the next day!!
I removed the vinyl covers and the problem IMMEDIATELY went away.