I have a little past experience with my old Trans-Am and car covers.
It can be very good to protect from sun damage, If you have to park under pine trees as I did for a while it's a godsend.
You really need to keep your car rinsed off otherwise the grit on your car acts like sandpaper if the wind starts rustling the car cover around. In my case it actually rubbed a bare spot on the back edge of one spoiler and along the side of the "shaker" intake on the hood. I was NOT happy about that.
Plus a wet car cover is a royal pain and they seem to mold up super easy.
I wouldn't do it again. You are better off doing a good wax job and keeping it rinsed off regularly.
I've become very fond of Meguiars Ultimate Liquid Wax
because I have a black car and it doesn't leave white residue at all and it seems to hold up pretty well overall.