I've worked in a lot of body shops and always liked the radiant-type heater. they heat the objects and fixtures in the room instead of the air. so when you pick up a steel tool it's the warmest thing around, instead of the coldest. and when you open a door you don't lose all your heat, as happens with a forced air type heater. all that warm air goes away. also much better for drying paint and such. I just finished building a new house and after much deliberation went with a Schwank radiant gas heater. wound up being only a few hundred dollars more than the two forced air units I would have needed. also MUCH more economical. it's an 80,000 BTU burner and about 40 feet of tube. very nice heat, and not too hot if you get close. garage is about 1200 square feet in an 'L' shape. Don.
ps. the two post hoist gets here next week. hee! hee! hee! this has been a LONG time coming. two sinks, a toilet, 11 foot ceiling, lifting beam, 10 8-foot flouresent lights, exhaust fan, air-conditioning, fridge, TV, as my wife likes to say, we built a new garage with attached house.