[Licensed to kill]

I had in floor heat in my last garage and now have over head radiant in both my garage and my shop. If you are only using the space to work on cars in the winter and don't expect to open the big doors, in floor is nice. Of course if you already have your concrete floor then that's out. Overhead radiant (gas fired), IMO is the way to go. Easy to install, cheap to run, WAY quieter than forced air and no fan to kick up dust.