Thanks for sharing! I didn't realize there was another argument out there about this. I'm sure you're right about certain vehicles being more streamlined for efficient airflow. I wonder if there's a certain speed at which this becomes more relevant? For instance, at 35 MPH, it's better to have the windows down, but as soon as you get to 55 MPG, the drag starts to take away from the MPG.

All I can say for certain is that in my experience, having the AC on (with my Prius C Three hybrid) always gives me worse MPG. I haven't noticed that leaving the windows down affects anything significantly enough to notice a decrease. That being said, it's also possible I have this bias since I didn't know it could be a wash and paid less attention. So many factors! lol