Obviously you live in the south

In colder climates, electric block heaters are installed on cars to keep the engine from freezing overnight (or if you go to the grocery store, etc). We have them in Maine, and Alaska... well, let's just say they have colder winters than we do.

There have been a few times when I've left my car running in the lot when going to a movie. You have to live in a very crime-free area to get away with this, though.