I have been using covers on my cars for years, both in the garage on outside. I have had the best luck with the covers made by California Car Cover Co. I tried a couple of covers from the online vendors.. Most of which were of pretty poor quality.
I prefer the heavier cover, Cal Car Cover calls it the "Noah" ... This is a very thick breathable material which provides great protection for indoor use while at the same time provides excellent protection outdoors.
Some of the on-line vendors have a material similar to the 'Noah", however, the on-line vendor's covers are not vehicle specific... They tend to make one size fits all regardless of what vehicle you order a cover for..
I bought my first cover from Cal Car Cover in about 1987. It was for my '57 T-Bird.. I still have the T-Bird and the cover...