Hi #again, when I looked in to this it was not so much the fact the air is being dehumidified and more the fact that air is being circulated - My problem was the garage was just too damp being built in to the side of a hil. I suggest an experiment with just an ordinary desk fan to start and see if that resolves the problem you have
In terms of a cover it does hot stop damp air getting to the car, being breathable means it allow air to get to the car, it does not dry it on the way through the material !
Aidan