# What's best fuel economy: Air Condition On or Windows Open? **URL:** \ **Category:** In My Humble Opinion\ **Created:** [July 12, 2013, 8:22pm UTC](https://boards.straightdope.com/t/whats-best-fuel-economy-air-condition-on-or-windows-open/663354 "2013-07-12T20:22:23Z")\ **Posts on this page:** 10\ **Page:** 1
**Author:** ![PastTense](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/pasttense/32/14550_2.png) [@PastTense](https://boards.straightdope.com/u/PastTense)\ **Post date:** [July 12, 2013, 8:22pm UTC](https://boards.straightdope.com/t/whats-best-fuel-economy-air-condition-on-or-windows-open/663354/1 "2013-07-12T20:22:23Z")
In order to keep cool in the summer while driving what provides the best fuel economy: having the air conditioner on or leaving the windows open? ---
**Author:** ![Skywatcher](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/skywatcher/32/254_2.png) [@Skywatcher](https://boards.straightdope.com/u/Skywatcher)\ **Post date:** [July 12, 2013, 8:49pm UTC](https://boards.straightdope.com/t/whats-best-fuel-economy-air-condition-on-or-windows-open/663354/2 "2013-07-12T20:49:53Z")
[Depends on the speed.](http://www.straightdope.com/columns/read/2961/has-auto-ac-been-improved-so-much-it-s-no-longer-an-energy-sink) > [@](#): > > The Straight Dope, October 1, 2010 > > GM wind-tunnel and proving-ground tests showed drag was negligible at city speeds, meaning you were better off with the AC off and the windows down. At speeds above 55 miles per hour, though, the opposite was true — open windows reduced gas mileage 20 percent while AC reduced it just 10 percent. The crossover point was 40 mph. ---
**Author:** ![Ranger\_Jeff](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/ranger_jeff/32/2065_2.png) [@Ranger\_Jeff](https://boards.straightdope.com/u/Ranger_Jeff)\ **Post date:** [July 12, 2013, 11:44pm UTC](https://boards.straightdope.com/t/whats-best-fuel-economy-air-condition-on-or-windows-open/663354/3 "2013-07-12T23:44:41Z")
I can’t offer a link for a cite because I don’t feel like searching the Car Talk site for the podcast. But on a program where this question was asked the brothers agreed that for maximum fuel economy, under 45 mph they recommend windows down and AC off. Over 45 mph, windows up and AC on. ---
**Author:** ![drewtwo99](https://avatars.discourse-cdn.com/v4/letter/d/d07c76/32.png) [@drewtwo99](https://boards.straightdope.com/u/drewtwo99)\ **Post date:** [July 13, 2013, 12:16am UTC](https://boards.straightdope.com/t/whats-best-fuel-economy-air-condition-on-or-windows-open/663354/4 "2013-07-13T00:16:08Z")
How about maximum efficiency: Windows up and no A/C at all 😃 ---
**Author:** ![Kent\_Clark](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/kent_clark/32/105_2.png) [@Kent\_Clark](https://boards.straightdope.com/u/Kent_Clark)\ **Post date:** [July 13, 2013, 12:48am UTC](https://boards.straightdope.com/t/whats-best-fuel-economy-air-condition-on-or-windows-open/663354/5 "2013-07-13T00:48:07Z")
[The Master Speaks.](http://www.straightdope.com/columns/read/1010/what-gets-the-better-gas-mileage) ---
**Author:** ![NorthernBiker](https://avatars.discourse-cdn.com/v4/letter/n/50afbb/32.png) [@NorthernBiker](https://boards.straightdope.com/u/NorthernBiker)\ **Post date:** [July 13, 2013, 7:57am UTC](https://boards.straightdope.com/t/whats-best-fuel-economy-air-condition-on-or-windows-open/663354/6 "2013-07-13T07:57:59Z")
> [@drewtwo99](#): > > How about maximum efficiency: Windows up and no A/C at all 😃 Yup, that’s how I roll, except AC really isn’t needed in AK. So it’s a win win. Could always go old school and mount a swamp cooler in your vehicle. ---
**Author:** ![Bosda\_Di\_Chi\_of\_Tricor](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bosda_di_chi_of_tricor/32/16845_2.png) [@Bosda\_Di\_Chi\_of\_Tricor](https://boards.straightdope.com/u/Bosda_Di_Chi_of_Tricor)\ **Post date:** [July 13, 2013, 10:57am UTC](https://boards.straightdope.com/t/whats-best-fuel-economy-air-condition-on-or-windows-open/663354/7 "2013-07-13T10:57:50Z")
> [@drewtwo99](#): > > How about maximum efficiency: Windows up and no A/C at all 😃 > [@NorthernBiker](#): > > Yup, that’s how I roll, except AC really isn’t needed in AK. So it’s a win win. Could always go old school and mount a swamp cooler in your vehicle. Try that in Tennessee, I dare ya. No, I don’t. And if you **do** try it–do you prefer roses or lilies at your funeral? Heatstroke is no good, bub. ---
**Author:** ![Loach](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/loach/32/350_2.png) [@Loach](https://boards.straightdope.com/u/Loach)\ **Post date:** [July 13, 2013, 2:27pm UTC](https://boards.straightdope.com/t/whats-best-fuel-economy-air-condition-on-or-windows-open/663354/8 "2013-07-13T14:27:24Z")
Mythbusters: [Mythbusters - Save more gas with AC on or Windows down Ans with AC - YouTube](http://m.youtube.com/watch?v=t7Je_995cdI) ---
**Author:** ![california\_jobcase](https://avatars.discourse-cdn.com/v4/letter/c/9d8465/32.png) [@california\_jobcase](https://boards.straightdope.com/u/california_jobcase)\ **Post date:** [July 13, 2013, 3:59pm UTC](https://boards.straightdope.com/t/whats-best-fuel-economy-air-condition-on-or-windows-open/663354/9 "2013-07-13T15:59:38Z")
It also depends on the vehicle. They are not all aerodynamically equal. Anyone who really has to know can buy a Scangauge II or Scangauge e to monitor the mpg in real time, is the car is a 1996 model or newer. ---
**Author:** ![DMark](https://avatars.discourse-cdn.com/v4/letter/d/e68b1a/32.png) [@DMark](https://boards.straightdope.com/u/DMark)\ **Post date:** [July 13, 2013, 6:00pm UTC](https://boards.straightdope.com/t/whats-best-fuel-economy-air-condition-on-or-windows-open/663354/10 "2013-07-13T18:00:30Z")
We really don’t have the option to think about that in Las Vegas. Years ago, I was driving our Saturn SC2 to work…about a 20-30 minute drive on the freeway. One summer Monday, the AC went out and I wasn’t getting paid til Friday and thought I could wait until then to get it fixed. Wrong. Do you have any idea what it is like to get into a car that is probably 180 degrees (sitting in the sun all day) and just rolling down the windows to drive a on freeway? It is like someone has two hair dryers at full blast shooting into your already toasty car. I found the money and it was fixed on Wednesday. When it is already over 100 degrees in the mornings, driving without AC is really not an option - and saving 14 cents with fuel efficiency would probably be offset by the cost of hospitalization from heat stroke.