brenndatomu
Minister of Fire
The issue with running a duct to the garage is if you pump air in, there needs to be a "return air" duct too, and in a garage that could include bringing back gas fumes, etc. If it were me and I were determined to do this I'd put in a duct and return duct that could be closed off and only open them when I was out there...and make sure to close if you are painting, working on gas tank, etc. Now that I typed it out, it still sounds like a bad idea...