I have and will leave Finn alone in the car on occassion. He loves being in the car. If I have to run errands, I'd rather take him with me than leave him alone at home. I figure it's no different than leaving your dog outside with fresh water and shade. I don't consider myself a bad pet owner for doing so, either. I park in the shade, leave the windows all down enough so that he can almost stick his head out. I think the most I've left him is fifteen or twenty minutes, if there's shade. And, he always has fresh water in the car. That's why I don't see much difference in that and leaving a dog outside for half an hour or an hour. I treat my dog well and love him more than I love most people, but, I don't see the problem with leaving them in the car for a short period of time. I've sat in my car with the ac off on really hot days with him, just reading a book or something...and, we've both been fine. If the dog is barking and screaming, or looks like he's not handling it well, I see it as a problem. Finn just stretches out in the backseat until I come outside.