http://www.elreviews.com/best-garage-heater/  and there are some good recommendations on that article. I don’t know if I want to spend all the money on a vented furnace and have to cut a hole in the roof.

Baseboard heaters work fine in my garage.

Car exhausts put out a lot of heat... 😟

Interesting cigar discussion...............

....since it was put here, I say take all of your cigars, pile them in the middle of your garage, add some kerosene and light...should work well............

probably better options but I use a kerosene heater as needed

I like the stability of kerosene over time

just light it outside and put it back out there for ~10 minutes when you turn it off

Watch YOUTUBE...

I think? this is not applicable to you...

Some guy ran flexible heat hose piping in his garage floor slab when building it..he bought an electric water heater and a electric circulating pump...heats his whole garage...way cheaper than oil, gas, propane or straight electric....
Pretty ingenious idea...,
You probably heard of it before? I hadn't..

Infrared heaters are effective and a preference for many because it burns propane. BTU's vary and so does the coverage area, but typically, these units warm a large space in a very short time. The infrared heater attached to a propane tank is an added bonus to provide immediate warmth to a personal space. Like a sun lamp, this option creates warmth instantly.

This is what I use and honestly it works great for me granted I think I should have went for the single instead of the double. It takes up very little space, heats up my insulated 2 car garage very quickly, Makes for a comfortable place to smoke my cigars in the winter. If you want to go fancy the the electrical baseboard heaters are the way to go but any electrical heating element will run that power bill sky high. Me I can't afford the cost equivalent of another stove, hot water heater, or dryer (the three biggest power consumers in the home) but if you have it to blow then go for it I say.

https://www.harborfreight.com/30000-btu-tank-top-propane-heater-63072.html 

Modine Hot Dawg. Natural gas. Digital thermostat. I installed mine 20 years ago. Best thing I ever did.