Down here in my neck of the woods, there was a recent sad, unnecessary death of a dog due to either ignorance or stupidity. A man went to our local Mall and left his two dogs in the pick-up bed that had a cap, with no open windows on an extremely hot day. By the time someone rescued them, one apparently was already having convulsions and they couldn't save him. The other did survive. The man is facing animal cruelty charges. Take a look at this link - you will be surprised at how hot it can get in a car, even on a relatively "comfortable" day. Please - spread the word and keep an eye out for pets left in cars in the heat. I don't know what the laws are in NH, but here in MA, an officer can break into a vehicle if necessary to rescue the animal.
http://mydogiscool.com/x_car_study.php
Getting off my soapbox now . . . .