You do it. Sit in your car, in the direct sun, with the windows “more than cracked”, keys out to the ignition. It does get considerably hotter in the car - takes less than you think. Besides dogs don’t sweat like we do - heat only escapes through their panting. We all know that running in for milk turns into 15 to 20 minutes - unless you are at a C-mart type of place. I love my choc labs and take them many places, but if I am making a stop anywhere I leave them at home - to hold down the furniture, of course.
Someone is going to get bit while violating a dog’s space. Who is liable?
We used hot cars to make weight for wrestling in high school