I'd break the dog out. I've lived in Arizona for years and, at the peak of summer, I don't even sit in my car when I'm letting it cool down. It takes 10 minutes for it to even start cooling down when I'm leaving for the day.

Imagine then wearing a fur coat all over your body and sitting in the car with the windows slightly cracked. In 90 degree weather.

I cannot even fathom.

So, yes, I would get the dog out of the car. The same thing goes for a child.