miles per gallon dropped significantly.
They figured out that the wife used the car to pick up their kids at school. she'd often sit in the carpool lane for 10-15 minutes. In the winter/early spring, temps are 50-70 degrees. She'd sit with the engine off and the windows open. In late April, May, early June, temps are in the 80's and 90's with high humidity, so, mom sat for 5-10 minutes with the car running to keep the AC on.