Never fold your windows! Rolling them prevents permanent creases and marks. If you already have some creases and marks, heat from the sun on the glass will help eliminate them.
Any silicone-based product is great for lubricating zippers
If the seams in your cushions are coming apart, protect the foam from the sun. Foam can be reused when replacing the upholstery, however, if the sun damages the foam, you need to replace the foam, too.