Saving Gas By Turning A/c Off And Rolling Down Windows?

Consumer Reports’ auto-test department reports that the air conditioner reduces your car’s fuel efficiency by up to 10 percent. So to achieve maximum fuel efficiency, motorists should avoid using the air conditioner at speeds below 40 mph and travel with their windows down, explains Gabe Shenhar, senior auto test engineer at Consumer Report’s auto-test department.
“But as your speed increases to 45 mph, or highway speeds,” says Jason Toews, co-founder of GasBuddy.com, “wind drag becomes an issue. Driving with the windows down increases the drag on your vehicle, resulting in decreased fuel economy by up to 10 percent. Drive at speeds over 55 mph with windows down and you’ll decrease fuel economy by up to 20 percent or greater.”

Around town you may save some but on the interstate and some other roads of the like you do better with the window up and the ac on. Test have been done.

I don’t think there is much difference. The best way for you to find out for yourself is to fill your gas tank then on a long trip leave the windows down. Then fill tank at your destination. Then when returning to your departure point use your ac and fill the tank again. Note how much you filled your tank in both directions. Then you will know for yourself.
I save gas by driving 99% of time at 60mph, coasting to stop lights and never going over 2000rpm on tacometer when starting from a dead stop. Hope I have given you some ideas. Marty

Windows, air conditioning – does it matter?
There’s the old saw that leaving your windows rolled down creates an aerodynamic drag on your car, cutting down on your fuel efficiency. And there’s the notion that the fastest way to drain your gas tank is by running your air conditioning.
Neither one is exactly spot on.
Two separate studies conducted in 2005 by Consumer Reports and the automotive Web site Edmunds.com looked at how running the A/C and opening the windows affected the fuel economy of a sedan and an SUV traveling at highway speeds.
What they found was that running the air conditioner, while it did draw power from the vehicle’s engine, only reduced each vehicle’s fuel economy by about 1 mile per gallon. That’s not a big difference unless you drive an already gas-hungry SUV.
The Consumer Reports’ study revealed that, while opening the windows does increase the aerodynamic drag on a car, it does not have a measurable effect on the vehicle’s fuel economy even at highway speeds.
Bottom line? Do what’s most comfortable when driving on the highway since you’re not going to save a whole lot of gas either way, say experts.
If you’re driving around town on errands, you might save some gas rolling down the windows instead of using the A/C.

your driving habits in terms of slow smooth acceleration and absolute minimal braking have far far more effect than the AC versus the windows argument, and that debate depends highly on weather the vehicle in question is an aerodynamic sports car to begin with or if it is a brick of an suv where the aerodynamics are so bad you can’t disturb them

i actually heard it makes u lose gas lol. because when u roll down ur window ur less aerodynamic and makes u use more when driving.

About 2-3 MPG. If you’re going above 50 MPH then you will save more gas with the AC on because of aerodynamic drag caused by the open windows.

well when you do roll down the window your just killing yourself more with greenhouse gases but i guess thats better than paying for gas

That depends on the speed you are traveling at. If less than 60 kph (40mph) then you might see a savings, but at higher speeds (where aerodynamics really come into play) you create more drag (thus using more fuel) and lose any benefit. This is because the air rushing into the car disrupts the aerodynamics of the car. Got this information off a motoring show some time back.

None!
It was actually tested on the Myth Busters and determined that by rolling down your windows you create enough extra drag to counteract any beneficial effect of keeping the AC off.