I have a California Car Cover on my Road Runner for about 2 years now that I used to throw on my Charger for the winter in the garage for over 25 years. It has still held up well even outdoors. I don't really use it to protect the car. I mainly use it to hide it as an eye sore from the neighbors. (Yeah, it is that rough of a project car). I did notice the other day the cover was starting to turn a little green in a few spots, has moss or algae starting to grow on it from the tree above. It will probably need a good power washing once spring comes back around.