I bought this cover for my 1966 coupe, It's fairly expensive and you can easily find a much cheaper one that works with pretty much any car. But if you want a great cover for your vintage mustang, this one is great!
Firstly: it fits great, although on my 66 the rear is a little saggy.
Second: it's super easy to put on the car aswell as to stuff it away in the bag that is provided for the cover. Unlike trying to stuff a sleeping bag into the bag for them, i just quickly roll the cover off of the car and fold it a few times and it easily slips into the bag.
Third: it's fairly waterproof, I'm not really sure where to stand on this. on some places the water just rolls off the cover and gave me the impression that the cover was water repellent. but on some spots the cover absorbs the water... Anyhow after it had rained once, I went out and lifted the cover and the car was dry, so thats good.
all in all a great but fairly expensive cover, but if you want to invest a little more in a better cover for you