It looks like I am going to have to store one of my old Mopars outside this winter. I will be able to park it on our patio under an awning so it will at least be covered from the snow (other than what blows in when it is windy). What I was thinking of doing and would like some opinions on is I still have a large swimming pool cover from when we had our pool. I was thinking of laying it out on the patio, parking the car on it, putting a regular car cover on the car and then pulling the remaining part of the pool cover up and over the car to completely envelope it. Then I would tie the pool cover down. Do you think this would be O.K. or could it possibly create a problem with dampness/moisture being trapped inside?

Using the pool cover may keep in water when you want it to breath

Agreed. Parking it on top some sort of vapor barrier is great, but I would not envelope it as you are describing, for the same reason as Clanton suggests.

The car needs to breathe or you will trap moisture. I don't know how it would work outside but a local guy spreads charcoal briquets on the garage floor under his car. They act like a desiccant and seem to help keep vermin away. I've also heard of people using charcoal in the car. An open bag in the front and one in the back to keep the moisture in check. The pool cover underneath with some charcoal and don't completely seal it may be a good recipe.

i stored one outside, made with the old blue type windbreaker material. i didn't tie it right and the wind flopped it and rubbed some paint off it. but that was in the early 90's. charcoal is a good idea as i put it all around the inside of my house to help humidity. humidity stays at approx 50-53 %. so it works pretty good. also, maybe put some drier sheets/mothballs to help keep critters out.

Can you put a curtain around the awning? Then just use a car cover.
If it's a nice car, I'd be storing it indoors somewhere - storage unit, rental, whatever...
Nothing is more expensive than paint, not to mention rust or bodywork.

My stuff sits outside every winter. If the car can sit on a cement patio with an awning cover, it will fair pretty well. The pool cover under the car may not be a bad idea if you can keep it laying on the ground, Sheets of plywood also work. A viper bearer between the car and the cement will be helpful, but there is no way I would wrap a pool cover over top of it. You need to be sure snow doesn't build up under the rockers, the air has to be able to pass under the car.

You will also want to do something to keep the little critters out of the car. Mice around here use dryer sheets for building nests. Gene

If the paint is shot, just use an outdoor car cover or tarp. Uncover it when possible to let it breath.

If the paint is good, wax it up good and leave it uncovered. The wind will whip a cover around and rub the paint on the edges.

I stored my driver 67 Vette outside for 6 years with just a cover on it.. At one time the cover and 2.5' of snow on it. Never any sign of rust on the frame. I know it is plastic so apples and oranges, but the frame and birdcage stayed mint. Let it breathe...

I have used a good car cover with a tarp over it as water can go thru any car cover eventually. This was a project car that needed paint so wind chaffing was not a concern. If the car has nice paint you do not want whatever you put on top to move in the wind or it will wear thru the paint on the top edges.

Don't park anything on dirt or grass either. Sheets of plywood are cheap.

Do whatever you can to keep the critters from building a nest in the engine compartment, or nibbling on rubber or vinyl, like wiring. Or any place else they might find pockets to build a nest. Make sure all the body plugs are installed and tight.

We stored my fiancé's car outside for 2 years during the Winter. It was not under an awning, just sat in the driveway. I put a cheap cover on it and then a big tarp; I ran bungee cords under the car to keep the tarp from moving around. Never had one issue.

Cleaned and dried the car, let it sit for a few days and then threw the cover and tarp on.