Aircooled VW South Africa

Dude, genuinely, if you have the car outdoors, don't put a cover on it. Rather create a shelter using shade cloth on your existing structure if you can't afford to store vehicle away indoors, thus protecting it from the harsh sun, but keeping it "dry".
Car cover outdoors as has already been alluded become a lekker "grinding paste", unless you intentionally wanting to create a patina effect

The car is under a carport which has a cement floor and shade cloth on 3 sides.