I've never gone to the extent of covering the car. I'm east of Lake Huron, and south of Georgian Bay ( snow belt ). We get enough snow here that I'd never be able to remove a cover from the car with so much snow on it. It's not unusual for us to get a foot or two of snow in a storm, and it can be much more than that with the squalls coming in off the lake / bay. Still, if you have a nice vehicle, it is worth keeping it washed in the winter to break that chemical reaction between the salt and any exposed metal. Luckily, corrosion by salt is a slow process, so as I said, even if you get fresh salt on the car right after a wash, it takes a little bit of time before it starts reacting with the metal. By washing, you've broken that chemical chain. Just remember to keep a little bottle of lock de-icer handy. I make my own. It's just methanol (methyl hydrate) that you can buy in the paint section of any hardware store. Put a little in a squirt bottle (nasal spray type) or a small trigger sprayer type bottle to shoot into your door's key hole. The methanol melts the ice in the tumbler almost instantly.