[EpicEng]

>however, idling is as (or almost as) effective as low-speeding driving at warming the passenger area.

Again, twenty years of turning the car on, going inside for 15 mins, and coming out and sliding into a warm car.

I'm not anywhere near knowledgeable enough to explain the details. I am fairly certain however that I was not hallucinating this throughout my entire childhood and young adult years.