The Burner doesn't blow out more than a foot if even that. The heat is pretty intense in the front for about several feet though. I think my manual says you have to leave 8' clear in front.
If it's a attached two car garage I would look at something like
this. It's electric so you don't need to cut a hole in the roof for a vent pipe (the gas one's need to).
All you need is a 240v drop installed in the garage. Any electrician can do that or depending on where your Breaker Box is in relation to the garage you can do it yourself.
Also the unit needs to be wired up. Again something you can do or have an electrician do it.
All sources of heat that have a combustion-able fuel source need to be ventilated. So with the Reddy Torpedo Heaters you have to leave the garage door open, which in turn lets out the heat.
I've had my Kerosene Torpedo Heater now for several years and while it puts out a lot of heat very quickly the fumes suck. When I come in the house after being any where near the thing my clothes smell the way my dad did when he came home from work (he was a N.Y.C Firefighter).
If I owned a home and wasn't renting and knew I wanted to use my Garage as a work shop I would've gotten one of those ceiling mounted Heaters. Floor Space is a premium when working in a garage. Another vote for getting the heater up and out of the way
MorBiD