I have had very good luck with covers that I purchased at Pep Boys.

I have purchased about 6 different covers, and the Pep Boys covers, made by Bondtech have served me well - they are blue, a non-woven fabric with a thin plastic covering on both sides - they have tiny perforations to allow for breathing.

One thing that seems to separate these covers from others is that they seem to stay cleaner than others.

When I used one of these covers for a station wagon with a rack, I used a pool float to keep water from collecting inside the roof rack.

For your car, you might want to use two floats.

My weather includes snow and ice, and these covers have lasted more than 2 years.

Get a cover for a large station wagon and fit both ends and make a fold on top of the car near the grommets for a rope.

I add small loops to the grommets so that I can use 1/2 inch diameter rope for tie downs.

I pass a rope through these loops and completely around the car. I then add loops to both ends of the rope, and cinch them up with a bungie cord between the rope loops.

I put one rope at the middle of the car and a rope in front of the front wheels, and behind the rear wheels.

The tension provided by the bungie cords allows you to adjust the cover so that it fits snug - My covers have withstood several hurricane-like rain storms and winter winds.

Using these methods, I fit a cover for a 740 wagon to my 544 that must sit out now that I have a '54 Chevy with a custom paint job in my garage.

For extra protection, you could custom cut an inexpensive blue tarp so that it just overlaps the car about one foot on the sides and front and back - that way this tarp will not collect condensation. Install it under the cover.

Today the wind chill is below zero and we are expecting a 12 inch blizzard.