The problem with garages are the concrete floors...they "sweat". Bike owners are well aware of this as when you go out in the AM and find all ur chrome fogged over! The cure....rug between the vehicle and concrete......its an insulator( or sponge)

 

I've heard that...last year was the first year I tried it and it seemed to work... I know before I would have water spots all over my truck from this happening...

 

It sounds odd but I put a couple of old house ceiling fans in my pole barn. They keep the humidity off the vehicles and toolboxes. They seem very efficient also.