Fuel Economy, Hypermiling, EcoModding News and Forum - EcoModder.com - View Single Post - When does having your windows down start to effect your mileage?

Big Dave · 03-10-2008, 08:26 PM

This has been a topic of discussion amongst Ford Super Duty owners. The general rule of thumb is to run with windows down up to about 35 MPH. Above that, the aero drag penalty exceeds the A/C load and it is better to run the A/C.

I have WeatherTech visors which are similar to your and they give me a third option in some weather conditions. I can run with the windows down to about a half inch above flush with the bottom of the Weather Techs and get decent cooling without the drag penalty. When the window gets lower than a slight overlap, you can feel the drag increase.

03-10-2008, 08:26 PM	#6 (permalink)
Big Dave Master EcoModder Join Date: Jan 2008 Location: Steppes of Central Indiana Posts: 1,319 The Red Baron - '00 Ford F-350 XLT 90 day: 27.99 mpg (US) Impala Phase Zero - '96 Chevrolet Impala SS 90 day: 21.03 mpg (US) Thanks: 0 Thanked 186 Times in 127 Posts	This has been a topic of discussion amongst Ford Super Duty owners. The general rule of thumb is to run with windows down up to about 35 MPH. Above that, the aero drag penalty exceeds the A/C load and it is better to run the A/C. I have WeatherTech visors which are similar to your and they give me a third option in some weather conditions. I can run with the windows down to about a half inch above flush with the bottom of the Weather Techs and get decent cooling without the drag penalty. When the window gets lower than a slight overlap, you can feel the drag increase. __________________ 2000 Ford F-350 SC 4x2 6 Speed Manual 4" Slam 3.08:1 gears and Gear Vendor Overdrive Rubber Conveyor Belt Air Dam