You may find pulling a cover on & off the car ,especially in dusty conditions, will cause scratching over time. Over here, some time ago, you used to be able to get a cover that was on a frame that folded out back to front over the car (rather like the hood on a convertible or pram) so the cover never touched the car. They are still made, it may be listed as something like a portable garage.
Found it it is called a perambulator garage
Try this link Item I am talking about is the right hand picture from google search
Portable Garages
Google also shows several suppliers of normal covers