Car Covers ?

Obviously, avoid any generic sized as "S, Med or Large" or any "one size fits all", also avoid any thin lightweight inexpensive covers.
California car covers are custom fit, and they clean up great in any x-tra large washing machine. Mine was bombarded with bird crap, just followed the directions using Simple Green and drip dried. Looks like new.
They're not cheap, but you definitely get what you pay for.