The garage metal does get hot with the sun on it. I am going to have a motorized screen installed and let it keep the garage cool

One way to cool your garage a bit is to leave the garage door open at night with the screen door closed. If your garage faces East, at least, open the garage door in the morning while the sun would be shining one it, screen door closed, and close the garage door when the sun is high enough so it no longer shines on the door.

If you want to HEAT your garage in the summer, by contrast, park a ton of burning hot metal inside and close the door. If the ambient temperature is 90°, a car with a hot motor that has been parked in a sunny parking lot somewhere will radiate heat into your garage for hours. If you don’t want an even hotter garage, one good choice is leaving your car parked on the driveway until a couple hours after sunset if it is hot.