David Rizzo: Hi, I am Dr. David Rizzo better known as DR. ROADMAP. Now we are going to discuss how to drive your car to improve gas mileage. Host: Is it better to use the AC or keep my windows open?
David Rizzo: This is one of my favorite topics because it goes back and forth but on the whole engineers agree it's better to roll down your windows and shut off the air conditioning. Yes people say, oh, well air turbulence is created but on the whole it's better to shut off the air conditioning. Here's why, first of all air conditioning saps about 5-15% of engine power. So you are wasting all that gas just to stay a little cooler. Now it can be modified. In other words if you are going down the freeway at 70, I will roll up the windows because then the Coefficient of Drag is so great at 70 that it makes a difference. But if you are in stop and go traffic in the city or going up hills, shut that air conditioner off, roll down the windows, you will save a ton of gas.