Kate, nice job on the testing....

I had suspected as much, because the real-time MPG meter just goes WAY DOWN when I turn on the A/C, and correspondingly, I have not really EVER noticed it drop significantly when I merely rolled my windows down.

Living in Phoenix, this summer has been WAY HUMID ( for us, anyway ) and the A/C in my car has been on far more than last year, and my lowered MPG is a testament to that, dropping about 3-5 MPG per tank average this summer versus last because or using the A/C more. I have used the windows when I can, but the opps have been fewer this summer......