Just don’t do it to my car. I have a properly prepared dog van.
Ditto that. When I went to Agility shows I had a silver reflective sheet to cover the whole van, vent lock for the rear door, cast iron mesh door, padlocked, so the vans' side door could be open, 12" fans running inside, wood panneling inside, temperature gauge inside, drinkers in the crates, and took turns with friends so the dogs were never unattended in our parking group.
*Before the van, I used a pop-up gazebo to cover my car for shade.
Any days too hot to compete I just pulled out of the classes, and when I was teaching I called off classes on very hot days [ well, evenings really, as Summer training I kept to the evenings specifically to avoid the hottest hours in general ].
When I hosted a few dogs shows I had posters in the car park and notices on the schedules stating dogs in hot cars would be retrieved by any means necessary, in other words, if its hot, don't leave a dog in the car unless you want the windows smashed to get the dog out. No one could say they were not warned - and we never had to action it I am happy to say !
What also shocks me is seeing so many people walking their poor dogs in the full heat of the day, they don't seem to notice their dogs flagging badly and I bet they never consider the heat of the pavement on their paws !