Surprise: Using car's air conditioning saves gas

Discussion in 'Fuel Economy' started by JohnM, May 25, 2015.

  1. some_other_dave

    some_other_dave Well-Known Member

    I have a buddy who put a 2.2 liter 911 engine in one. I also know of someone who put a 3.2 liter 911 engine in one. I hear it's really funny to see the looks on the faces of drivers that you pass while driving a Bus--going uphill. While towing a trailer...

  2. thunderstruck

    thunderstruck Super Moderator

    Part of the secret is turning temp up on AC so it doesn't kick on any more than needed. I had ceramic tint put on my car which helps a lot with heat rejection. Especially with black seats, and no, I didn't have a choice of interior colors or I would have chosen white.
  3. phoebeisis

    phoebeisis Well-Known Member

    It is Hot and Humid in NOLA- 8 months a year.March thru Oct.
    I ran the AC all the time because my wife would have killed me if I didn't.
    Now I will try to run it when I am coasting down a bridge
    or coasting to a redlight
    But in general if it is hot enough to make me sweat-the AC goes on.

    The Suburban is white-good thing-but the Prius is black with black interior-terrible in NOLA(good price on it in 2006-I would never buy black if it wasn't a great deal)
  4. jcp123

    jcp123 Caliente!

    Depends on the car. Even on the freeway where ac should hold it's advantage, my best ever was 43mpg vs damn near 51 without, normally closer to 45-47. I have come to the conclusion though that my ac is just a really inefficient one. In-town I usually get at least mid-30s but my best with ac is 28. Manifold gauges and such confirm it is charged and running normally.
  5. nerfer

    nerfer Member

    Let's see if this image works. I took some readings with my Prius using a scangauge. Now keep in mind, this is low speed, short distance. The OP is about long highway trips which are completely different (for one thing, once the A/C gets the car cool, it won't work as hard, but I didn't drive it that far, so for me it was worst-case).
  6. EdwinTheMagnificent

    EdwinTheMagnificent Legend In His Mind

    I haven't done any controlled tests with A/C in my Prius , but my seat-of-pants testing says fuel efficiency in city/suburban driving takes a big hit. Maybe even 15%. I don't require it and use it very rarely.
  7. 08EscapeHybrid

    08EscapeHybrid Moderator

    Years ago I did a mini-experiment with my 98 GMC K1500. For one week, I drove with the windows up, and the a/c off, no matter how hot it got. The next week, I drove with the a/c on max, all the time, no matter what the outside temperature was. The difference in mileage was less than 1 MPG - pretty much statistically insignificant.

    In the FEH, it is hard to say, since the a/c will come on automatically if the pack gets too hot. That being said, if using the a/c on its maximum settings, it does not let the vehicle enter electric mode.
  8. S Keith

    S Keith Well-Known Member

    IMHO, .8 mpg loss on 16 mpg (5%) is statistically significant particularly when A/C demand is so amazingly small for a K1500 compared to a smaller car.
  9. jcp123

    jcp123 Caliente!

    5% is pretty good compared to the 10% on the freeway and 1/4-to-1/3 hit the Echo takes in the city. 5% would be enough to just offset the summertime heat gains and keep a pretty constant MPG all year, so I'd take that number all day long!

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