How do you cool a garage in a very hot climate? Because they aren’t considered living areas, garages and garage doors are typically either poorly insulated or not insulated at all.
Adding an air conditioning solution to your garage is probably what everyone (including that pesky voice in your head) has already suggested but from a financial perspective, it can be quite inhibitive. There are some other options
By making sure that your garage is ventilated, you are taking care of part of the problem right there. Since hot (or hotter) air rises, it makes sense to have ventilation in your garage roof.
If you have the flexibility, and wherewithal, consider painting your garage a light color like white, light gray, a subtle yellow, or cream. Dark colors attract, or absorb, heat, light colors reflect it.
If you’ve been out driving and your engine is radiating heat, why would you add to the heat problem you already have? Park your car in the driveway until you’re finished working on your project for the day.