I just bought a Shelby GT and I was wondering what would be the best car cover to buy to keep it in good shape. I don't have a garage.

 

check out Covercraft. I just got one and the quality and fit is great.

 

Coverking makes some good cover as well...

 

Keep in mind, if you don't want the cover to do more harm than good - you'll need to make sure the car is dust/dirt free when covering it. Anytime the wind blows and that cover and shimmy and shake around, it's going to put light scratches in.

Sometimes it's better to just keep the car clean as possible and use good waxes or sealants.