Is it possible to vent the hot air from a garage?

Hot air rises so placing a vent into the roof will allow the heat to escape naturally. Or you can buy a solar vent that drives a small fan to push the air out when the sun is shining. Make sure you have the vent properly installed to prevents leaks, birds, etc from entering the Roof or garage space You can add vents in your garage, but make sure that you are not breaking the fire rated drywall which is on any walls attached to livable space. This drywall is thicker and usually marked as 5/8" fire rated drywall. If you do cut into the drywall you should re-tape and mud around the opening for safety.