My 6 car garage is 30 feet wide and 75 feet long. The front 2 spaces are 25 feet deep and 30 feet wide. On the right hand side is 50 more feet of 1 car wide space. the car storage is un-conditioned. On the left hand side is 1 car wide and 50 foot deep of air conditioned shop space. I put in a stairway to the attic and have 75 feet by 12 feet or so of Model A and 63 Corvette storage space. I can walk down the center of the storage space but have to duck on the left and right. I installed a 2 ton central system with 16 SER of which Obama paid $2000 for in a tax credit. I have electric heat but heat here in balmy SE Texas is rare, a few days a year. When it gets below 50F I hibernate in the house.