Conserving Gas…

2005_08_16_shell_gas.jpg(Photo courtesy of Lori Shepler/LAT.)

Today, the front page of The Los Angeles Times had an article about some of the beliefs motorists have about conserving gas:

In the quest to squeeze as much mileage out of their gas budgets as possible, motorists are exploring all the angles, gleaned from friends, family and even the Internet. Some work; others are urban myths.

Turning off the air conditioning and opening the windows, for example, actually lessens fuel economy because air going through the windows adds drag to the car.

[John] Myung is not alone in thinking gas prices go up on weekends, but experts say he’s wrong.

“That’s a bit of an old wives’ tale, a myth,” said Tom Kloza, chief oil analyst for the Oil Price Information Service. “Wholesale prices change every day, with the exception of Sunday. The biggest price moves tend to take place on the wholesale markets on Wednesdays these days.”

But there does appear to be truth to the theory that stations near freeways charge more.

Meanwhile, this morning, I started carpooling with a colleague from work. We’d been talking about it for months but we were finally able to synchronize our schedules and start the process today. Oh sure, there was that little dance at the end of the day about what time we could both leave the office together, but it was a minor inconvenience compared to the money we’ll save on filling up our respective gas tanks.

8 thoughts on “Conserving Gas…”

  1. Never thought I’d say this, but buying an old Mercedes diesel and converting for biodiesel never sounded so good.

    But, then, I don’t own a car.

  2. I’m surprised no other geek has piped up about this so I guess I’ll do it. “Mythbusters” on the discovery channel busted the myth of AC vs. Windows down. Two identical cars, same amount of gas, same rate of speed…the car with the AC blowing ran out of gas long before the other one.

  3. I’m not a car expert, but I’ve worked on a lot of car magazines, and every single car guy I’ve ever talked to has said it’s better on mileage to leave the windows up and run the AC. I didn’t see the show you’re talking about, but I guess the first things I’d wonder are:
    1. Did they replicate the experiment alternating the cars, so that the windows-down car in the first trial became the AC car in trial 2, and vice versa? There’s no such thing as two identical cars. One could need a tune-up, or have a leak, or a thousand other things you’d never think of.
    2. How fast were they driving? The drag you get from leaving the windows down is mostly a factor at freeway speeds. If they were crawling around on surface streets, they’d get a different result.

    Though personally I’d like to believe the Mythbusters show, because the AC on my car doesn’t work.

  4. summary of the Mythbusters episode here:
    Speed was 45mph.

    And from my memory: they performed the experiment with two of the same SUVs, driven at the same speed, same track, same time. Both had been given a tune up to the same specifications. The windows-down SUV went about 30 laps further on 5 gallons of gas. Still seems like it’s going to be “air conditioning uses gas” no matter how you look at it.

    My husband was not happy with me winning this one ;)

  5. They took 2 identical Ford Expeditions full of fuel, one with ac on windows up and one with windows down ac off. At 50 mph the one with no ac and windows down went 15 miles further. It is more fuel efficent to have your A/C on than your windows up at highway speeds because of drag. It’s not worth suffering the heat just for a gallon of gas. Besides, at higher speeds, you shouldn’t even have your windows down. On the highway, dust and other debris from trucks and other vehicles can come in at very high speeds and injure someone badly. Another idea — if it’s not too hot out, with the windows up (or mostly up) just turn on the fan w/o the AC, sometimes that works just fine.

  6. For anyone who is a Mythbusters fan, tonight’s episode is a flashback of Buster’s (the crash test dummy) finest (or worst) moments!

  7. amanuensis—you contradicted yourself….so in your opinion which saves more fuel; AC On windows up, or AC Off and windows down?

    The Mythbusters test showed that AC off and windows down works better.


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