Well, I'll jump in here. Questions: where do you live? How cold will it get? How much do you want to spend? You have 3 car garage, and if you are in Toledo, you are going to need either a lot of kerosene or get something better. For years I used bullet industrial "tubo" heaters, and they worked, but the fumes get to you after a while. I had to really seal up the garage [at the time in the Chicago area] to keep heat in, as it was an detached garage. If it had been in the Carolinas?? been a LOT better. It might take 2-3 of those turbos to heat 3 car space...and cannot imagine electic heaters pulling that off--especially the radiant. BUT am not an heating engineer. I would imagine your electric bill would bring someone to the door checking on your usage.
This time, [for 2 car space] I just went for a professionally installed gas heater on the wall, all to code. And it was worth it all. Up to 85 in January in about 20 minutes from stone cold 20 degrees? It has to be turned down or off or I bake. Good luck with your choice
..but do it safe, and right. Don't jury rig it just to save pennies.