Can winter gas be the cause of my sudden 10 mpg drop in fuel economy?

Discussion in 'Gen 2 Prius Fuel Economy' started by Cherril84, Dec 2, 2010.

  1. Cherril84

    Cherril84 New Member

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    Hello, I see a lot of posts from Prius owners about winter mpg drops, but many of them mention that they still use the heat and have gotten new tires. I still have my summer tires, rarely use the heat, and drive a little too much like an old lady..no sudden starts or speeding. I got 61 mpg up until mid-November, when I filled up on a new tank of gas, and noticed that I couldn't get up to the 60s anymore. I was able to drift in the high 50s on the expressway and get 60 + mpg, but now, if I try to go the speed limit or maintain any kind of highway speed, the mpgs just drop down to the 40s or 30s, even on flat pavement. I end up having to pump the gas pedal and release it in order to keep a 50 mpg average. This kills my battery charge, though, and I am soon left with 1 or 2 bars and in the purple. What else can I do? Do I need to put tape over my grill? Use Shell gas? Try to drift behind semis? I drive 300 miles a week to get to work, so I have to drive frugally. What can I do to save gas this winter?

    Thanks.
     
  2. donee

    donee New Member

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    Yep. But, check your tire pressure as cooler weather drops tire pressure 1 psi/10 degF.
     
  3. JimN

    JimN Let the games begin!

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    I doubt it is the gas. Historically with the grill blocked I've been able to hold onto the lifetime average or improve it.

    Check your tire pressure as I'm sure it has fallen. Have you explored other routes? A road with flatter terrain or a more consistant speed will boost the average.

    Batteries like to be comfy. Efficiency drops if they are too hot or too cold.
     
  4. Codyroo

    Codyroo Senior Member

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    A combination of things may lead to this

    1) Outside temperatures dropping
    2) Decrease in tire pressure (directly related to item 1)
    3) Winter Blend gasoline
    4) Moisture on roadways

    I've averaged 60 mpg on 9 of my last 11 tanks of gas (calculated). We have had some very cold weather recently and my last tank was 57 ish. This last fill up is somewhere around 56 mpg. We may have had our winter blend added, but the outside temperature is the biggest difference.

    Now, I realize everything is relative. Our "cold" morning temperatures have been in the 30 - 39 F range (roughly 0 - 4C). But the impact is noticeable. I can only imagine what the folks seeing 20's and below must see MPG dropwise. *and frankly, I only want to imagine it.....too darn cold for me).
     
  5. don_chuwish

    don_chuwish Well Seasoned Member

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    This evening it was 41F on a highway run I've done all year. I have the grill blocked now. It was foggy but not wet and FE was down about 2-3mpg from normal on pure highway 60mph running. Definitely cold related. (I checked my tires recently when we dipped into the 30s, and had to add a few pounds all around to get back to 44/42.)

    - D
     
  6. uart

    uart Senior Member

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    That will knock your MPG down a lot. Definitely not a good idea.
     
  7. jose987

    jose987 New Member

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    I have to agree with what Jim has to say. It got to with the Batteries. Are you aware that the battery takes a beating during a cold weather? It also happens during extreme heat. During winter, sometimes my car refuses to start and then I find out that its dead. It has happened a lot of time with me. Yah check your tires too properly.
     
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