valid point and whatnot - no argument. but, there's a part of this discussion that i'm never able to really understand. i spent hours in the car when i was kid, while i waited for parents to run errands on the way back from various things. there's a certain age where you don't really want to be seen walking through the mall with your parents, so i always asked to stay in the car - on the condition that they left the battery on, so i could listen to the radio or put in a tape. this allowed for the air conditioning to run. he'd take the keys with him. my memories spent in the car alone are consequently relatively positive.

i think that there's a larger problem with leaving a very young child or a pet in the car for a long period than the temperature. but, i'd argue that there's a relatively young age where it's not much of a concern for a short period, and that sometimes it's tactically the only real option. in those cases, it's not a very difficult task to leave the battery on to provide for air conditioning.

why that is never mentioned, i don't really understand.

deathtokoalas 
+tupen see, that's very true and everything. but, i think the likelihood of the fan failing is relatively remote. on top of that, chances are the air was on on the ride there. i'm not arguing with the premise: you don't want to leave your dog alone in a hot car for any extended period of time. but, you can't take your dog into a grocery store, for example, either. you could take them home first, sure, but that's not always reasonable. you could also just turn the fan on. it's probably better than leaving them outside tied to a pole or something in the searing heat.

as i mentioned, there's bigger problems with leaving very young kids in a car by themselves. i'd say that's up to around three, you've got abduction issues. they might randomly start choking, or...it's just irresponsible. but, once they can walk and talk, and be told to sit in the car and not open the door for strangers, and you're pretty sure they're going to listen to that request, leaving them in an air conditioned car for ten minutes doesn't strike me as much of a crime.

deathtokoalas
+tupen well, i think that physics kind of disagrees with you. but that's ok. there's only one way to find out: find a car in arizona and try it and get back to me on your results.

but, when you do the experiment, don't get into a car that's been sitting in the sun all day. leave the air on for a half hour first.