If you have pull down attic stairs, wedge them open with a piece of wood. They also make an Alexa controlled window fan made for our single hung windows. That's what I do. Your mileage may vary....

Screen shades
 

Curious about how you install screen shades over a garage door?

Door vents
 

They were useful when the older electric carts were being charged and the smell was unbearable.

Useless and ugly

Doing that will compromise the fire safety code that requires a separation between the garage and the attic. If a fire starts in the garage, the smoke will migrate to the attic and spread to the rest of the house. House fires are more likely to start in the garage.

hot air rises so how can vents on the bottom of the door help out?

Sorry, but not true.

Why would one pass this incorrect information on???

My garage door faces East, and it got horribly hot in the summer, even without bringing in a hot car. I installed TWO forms of insulation in the door: foam panels purchased at Lowe’s and foil-backed bubble wrap with a white front. (I ordered the second on line, then found out about the first and thought it might be better, and ended up with two systems, so I used them.)

Installation was made much harder by the many steel beams that secure the door in case of a hurricane. Those all have to be removed. An electric screw gun didn’t work well for that, but an electric impact wrench worked very well. The bubble wrap probably doesn’t help much, but it covers the entire backs of all of the steel garage door panels. The project took me three days, working three or four hours a day.

Before, if I touched the steel door on the inside at 10 am, it just about burned me. Now, it feels slightly warm. I would estimate that the garage is a good 20 degrees cooler now in the summer. In mid summer, that might still be 95°, but that’s better than 115°. In my first home in The Villages, I had a big garage to attic fan installed with two air vents in the door. But that fan drew quite a bit of electricity, and it was sucking in hot air from near the concrete outside the door. Without the door being insulated, it wasn’t much help. Even with just using the screen door while the garage door was open, the garage might still be 95° if the outdoor temp was 95° and the fan was on.

Now, in my new home in The Villages, my washer and dryer are in the garage, but it’s bearable, as I only need to be out there one or two minutes at a time. If I need to do some woodworking in the garage, I do it about 8 am, in the shade, with the garage door open.

Ugly vents
 

Vented gargae door are not the best looking addition for sure. They provide little to no help for the unattractive look. I'm surprised the powers that be allow them when you go to "Kiss the ring" to get approval for changes to the exterior. Good luck and stay cool.

I agree and the bad part is they all seem to rust which means the repaint becomes progressively worse. They are ugly and not needed.

Coupled with a thermost controlled ceiling fan (ours is from the Solar Guys), the vents help our garage stay cooler. Our garage faces south.

Well, OP, there you have it. Lots of misinformation and speculation in 27 posts. You will not get the correct answer here.

Not true. We have gas, no vents. Nobody in our entire villa neighborhood in Fenney has vents.

Garage “cooling”
 

1. Without installing some form of additional cooling device; typically a mini split, achieving anything less than outside ambient air temperature in the garage is not possible.
2. Since my garage is south facing I put in the following items:
A. Radiant barrier in attic over garage.
B. 3/4” decking in attic over garage.
C. Radiant barrier covers in attic over attic access panels.
D. Radiant barrier on inside of garage doors.
E. Two vents, one low on golf cart garage door and one high on main garage door.
F. One ceiling fan in garage.
3. Garage temperature is always within 5 degrees of outside ambient air temperature.