The importance of a heated garage

I tell you being from Jersey having a heated sealed garage is very important. You want to avoid condensation at all costs in the garage. I ruined a couple nice cars to rust due to condensation.

I know some folks used those bubble garages inside their garage to control moisture with good results. Keep that baby warm and dry

 

I purchased my car from New Jersey, it came from a heated garage. I live in Texas, so not only is my garage heated, but more importantly it is Air Conditioned!
I usually only cool the garage when working on stuff or if it gets over 105 on a regular basis. I also turn it on after parking a really hot car (Ferrari 360) in the garage, keeps the rest of the house from heating up.

 

I wouldn't know about condensation in the tank, etc - but in my experience fuel does go bad quicker if the tank is empty. What I do know is that if I keep a moisture killer inside the car during storage, after a few months there is quite a bit of water in there. My guess is the tank won't be very different and will trap dampness from the air.
I'm not taking chances and just fill up before storing, it's also nice to start the cars up in spring and find that their tanks are full.