gas wasting myths on the radio

[jwxr7]

So I was listening to the morning show for a lansing radio station this morning. They were discussing myths about wasting gas, they said that driving with your windows down will not negatively effect your FE . They also said running your AC will not lower FE . Does this sound right? They were agreeably right about idling actually wasting more fuel than shutting down and restarting. I didn't hear the rest of the myths they brought up. I e-mailed the dj to check out our great site. I could see trade-offs about when it is better to use windows over ac or vice versa? I think Peakster did a test with windows down didn't he?

[Peakster]

They probably got their information from here.

Windows, air conditioning - who cares?

There's the old saw that leaving your windows rolled down creates an aerodynamic drag on your car, cutting down on fuel efficiency. And there's the notion that the fastest way to drain your gas tank is by running your air conditioning.

Don't believe either one.

In two separate studies conducted in 2005, the automotive Web site Edmunds.com and Consumer Reports compared the fuel economy of both a sedan and an SUV at highway speeds with and without air conditioning and how open windows affected gas usage.

What they found was no significant difference in fuel economy in either sedan or SUV under either condition.

I know they're wrong about the window thing. I saw a 1.8% FE decrease with my windows open at 50mph (which really isn't that fast in the 'real' world). However to most people, 1.8% is nothing. 1.8% would also be hard to quantify in an SUV that has a Cd of 0.44 and gets 15 mpg to begin with .

[BluEyes]

Usually it is better to use AC than windows on the highway I thought.

It can also depend on how far down the windows are. My dashboard FE gauge never registers a difference unless the window is all the way down.

[jwxr7]

It probably depends on the vehicle too. A big engined non aerodynamic vehicle (SUV) may not show a difference because they are already so inefficient.

[jwxr7]

Yeah, you're right peakster here is the souce. http://money.cnn.com/2007/05/09/pf/g...ex.htm?cnn=yes

I guess significant difference can mean different things to different people.

[Bill in Houston]

Originally Posted by Peakster

I know they're wrong about the window thing. I saw a 1.8% FE decrease with my windows open at 50mph (which really isn't that fast in the 'real' world). However to most people, 1.8% is nothing. 1.8% would also be hard to quantify in an SUV that has a Cd of 0.44 and gets 15 mpg to begin with .

But if it was 1.8% at 50, than at 70, where some people spend a lot of time, then it could be at least 5%? Maybe? And maybe that is enough to make it worth it?

[minic6]

Large veh. have more torque and can handle the load of A/C better. They are also designed with A/C in mind. (Try and find a car that doesn't have A/C)
Problem with my Metro or any low displacement motor was that when you turned on the A/C the car actually slowed down, climbing even small hills took much more gas pedal input. It showed a 4 mpg loss in my car. So when it broke out it came. I liked the post with the hatch propped open. Reminded me that my car has crack open side windows. It has cut down on the buffeting in the car sooo maybe it helps?

[Hockey4mnhs]

i hate when that happens

[jwxr7]

Originally Posted by minic6

Large veh. have more torque and can handle the load of A/C better. They are also designed with A/C in mind. (Try and find a car that doesn't have A/C)
Problem with my Metro or any low displacement motor was that when you turned on the A/C the car actually slowed down, climbing even small hills took much more gas pedal input. It showed a 4 mpg loss in my car. So when it broke out it came. I liked the post with the hatch propped open. Reminded me that my car has crack open side windows. It has cut down on the buffeting in the car sooo maybe it helps?

When I bought my metro the ac came out right away. It was missing parts anyway. BTW, nice to see a fellow michigan metro on here .

[jkandell]

Originally Posted by jwxr7

Yeah, you're right peakster here is the souce. http://money.cnn.com/2007/05/09/pf/g...ex.htm?cnn=yes

I guess significant difference can mean different things to different people.

What they don't realize is that a series of "insignificant" differences can add up to something substantial.

[Bill in Houston]

Originally Posted by jkandell

What they don't realize is that a series of "insignificant" differences can add up to something substantial.

No single raindrop thinks that it is responsible for the flood...

[JanGeo]

Yeah if you open the rear windows just a crack it allows more air to flow from the front vents that in effect lowers the air pressure in the windshield area and probably helps fill in the turbulent air in the back of the vehicle. I would really like a big pipe flowing air out the rear hatch area from the front windshield area.

[VetteOwner]

depends alot on the car. my truck with the windows down makes a huge difference when its windy out than my chevette. its kinda eery cuz the chevette i had all 4 windows down one day and it wasnt anywhere near as strong of a breeze with my truck. and i could carry on a conversation going 55 without talking loud at all... i did find out somehting pretty cool tho. seem sliek theres a funky little airpocket around my windshield wipers cuz thier doing construction near my house and a whole lotta brown dust has settled on our cars. i went driving one day and noticed the dust at the very front of the hood was blown off yet as you moved back towards the bottom of the windshield it was alot more there. same with the roof line. very top half of the windshield and roof was totally clean but got dustier as you went back. now theres gotta be a huge swirly coud behind my car cuz the rear hatch was just covered! even tho the rear has a small but very obvious boat tail.