Six hours away from home–in and out of extreme heat. Between doctor appointments and grocery shopping, I was in the car hot as an oven. 
And, OMG, the miserable heat radiating up from asphalt parking lots!! Oh, so grateful for my cool and comfortable air-conditioned home.
Three Quarters & Counting 
I always put up a reflective windshield screen. I think it helps some, and if nothing else, helps protect the dash from the sun. But the cars sure get hot this time of year.