I have an Audi A3 Sportback cover... In fact I have those silver OEM manufacturer covers for each of my cars.
If they spend any time parked, they get put on tyre-cradles, pressures go up 5psi, and the car cover goes on. -This is indoors in a garage though... It keeps the dead flies off, and helps keeps the interior numbers nice and moderate. -Keeps UV fading down to a minimum also.
Tire cradles:
If you're storing your car long enough to make putting on a cover worthwhile, you should probably get some of these also.
Oh, and NEVER put a cover on a dirty car. -Here in Florida the air is always dusty with fine sand if it hasn't rained for a few days, and if you get a few grains of that trapped under a car cover, it does all sorts of damage. -It's EVEN WORSE if you put it on outdoors, because any wind will then 'ripple' and 'ruffle' the car cover material, and the ripples tend to tug 'rhythmically' at the cover material, which GRINDS the sand grains into the paint...
Keep your car CLEAN, and use the cover for storage. DON'T use one for everyday parking outdoors, unless you plan on washing the car every single day.
Keith