Does 50-degree fall weather optimize fuel economy?

Discussion in 'Gen 2 Prius Main Forum' started by Vespasian, Oct 20, 2005.

  1. Vespasian

    Vespasian New Member

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    All of a sudden I'm averaging over 60 mpg (62.0 mpg when I last checked), something I never expected to be able to accomplish. I don't think I've change any driving habits, and I'm still talking the exact same routes. Is it all because of the weather? BTW, I'm still prepared for my average fuel economy to go way down to something like 30 mpg (or worse) in the middle of January.
     
  2. geologyrox

    geologyrox New Member

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    LOL, that right there just made me realize once and for all just how easy we Floridians have it. I can't believe it's already 50 degrees somewhere, it's hard to imagine - it's still baking us daily, as per usual.
     
  3. Jack 06

    Jack 06 New Member

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    Vespasian: Can't explain your surge in MPG---as showing on your MFD, I assume? After how many miles on this tank?

    Maybe you're driving downhill too much :blink:

    You can PM john1701a, who lives in Minnesota, and who's been driving Priuses (first a Gen 1, now a 2) for four winters there. I thought he posted once he rarely got under 40. But if you drive under 25 minutes at a crack in the winter, you might do worse.
     
  4. tomdeimos

    tomdeimos New Member

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    My car seems to get its best mpg at about 70 degrees. At 50 is where it starts to degrade for winter.

    But you have to consider trip length too. A trip at 50 could be just fine. But my short commute at 50 doesn't shut off the engine as much and this costs big time. Warm up to stage 4 takes longer. So if you get past that, 50 might work great for you.

    I only commute 8-12 miles. Warm up takes over half the trip.

    Then to confuse things is the issue of when the fuel mix starts changing for winter!
     
  5. deh2k

    deh2k New Member

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    I think that the warmer the temperature the better the mileage, until the drag from the AC compressor brings it down. So I would say that the highest temperature that you can stand driving without the AC on (or the windows wide open) is optimal.

    My mileage went from the mid 50s to the lower 40s last winter. A friend at work who commutes longer distances than I do got in the high 40s in the winter. It makes sense that shorter trips take more of a hit with colder weather.
     
  6. efusco

    efusco Moderator Emeritus
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    Nah, not the temp in this case.

    Warmer is better as stated above...at least until it starts affecting the performance of the HV battery.

    I doubt you'll see the 30s for MPG this winter if you usually get in the 50s...probably down to the low 40s at worse.
     
  7. Jack 06

    Jack 06 New Member

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    I'm with deh2k. Optimal, for me, is about 80 degrees, just before the point where I need the AC.

    Testing (always filling up before and after each test), I've run without the AC up to 100 degrees, and found incremental increases right up to about 95. Don't know why that is. One of several idiosyncracies.
     
  8. DanMan32

    DanMan32 Senior Member

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    For me it isn't so much the heat but the humidity that has me use AC. And when I did turn it off and use recirc, I learned there were smelly diesels out there.
     
  9. john1701a

    john1701a Prius Guru

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    There is a definite threshold at 50-55 F degree range, but it's not the ideal. It is just a rather noticeable improvement compared to both colder weather and the hot/humid stuff that requires A/C.

    Each of the 5 winters, which here in Minnesota typically means below freezing temperatures for several consecutive months, I have rejoiced when the warmth returns.

    When the mercury climbs about 50, so does the MPG.

    But in the meantime, I'm going to have to deal with the 40's for awhile... dipping dangerous close to 39.9 MPG during the dead of winter here. Fortunately, the efficiency I experience then is still significantly higher than everyone else.
     
  10. jeromep

    jeromep Member

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    I have found that between 70 and 80 degrees is the best temp range and gives me the best economy. But the number of weeks we get which live in this "happy range" is not all that many. We come out of winter pretty quick, so late spring days feel like summer and early fall days are fairly warm, usually that means that we are above 80 degrees, or below 60 degrees, but not much in the "happy range" most of the year.
     
  11. TonyPSchaefer

    TonyPSchaefer Your Friendly Moderator
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    Vespasian, check out the link in my signature and you will see that the lowest I got last winter was low 40s. I'm hoping that with a year's experience I will keep above 45MPG. I can dream.

    Oh yeah, I'm in Illinois also so there will be some similarities.
     
  12. maggieddd

    maggieddd Senior Member

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    I also find it very strange that now when the temp. dropped to about 50s I am seeing 60.1mpg after 197 miles, I don't know if I will maintain that figure over the whole tank, but the best I've ever done in the summer over the whole tank was 58.8mpg. It could be due to my slower driving, though. Not sure, but I am certainly on my way to beat my record in the colder temperature.
     
  13. tomdeimos

    tomdeimos New Member

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    Enjoy it while you can. My mpg dropped to 45 today commuting to work! Till now I was running around 49 but today I had my first snowflake light! of the season!

    Same commute in 70 or warmer weather I get like 54 mpg.

    Will start winterizing this weekend, so that should help a bit.
     
  14. maggieddd

    maggieddd Senior Member

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    what exactly do you do when you winterize?
     
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