My mother has a Yorkie whom she adores. We were at DLR in late November. The car was in the shaded parking garage. We left him in the car and came back a few times during the day to check on him, make sure he was comfortable, had a bathroom break (we, of course, cleaned up after him). My mother has never put him in a kennel. She takes him everywhere and feels that the stress of other dogs and the strange circumstances (not to mention the germs and possibilities for disease) would be too hard on him (he's fairly old). Her dog did just fine that day. He goes with her in the car all the time when she runs errands, waits for her while she shops and eats. He's happy as a clam in the car. Of course, we would never do this if it were hot. However, the situation was not at all problematic. We'd have been furious if anyone had called the police.