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Disappointing hwy MPG

Discussion in 'Prius c Fuel Economy' started by cyclopathic, Nov 17, 2015.

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  1. cyclopathic

    cyclopathic Senior Member

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    was traveling last weekend. After stopping for gas and pulling back to interstate, "from the start" MPG was holding on at steady 38-39MPG. This is on flat surface with cruise set at 73mph, ECO on and instant consumption staying in green zone.

    and it was like that for 1.5-2hr, until we pulled to lower speed limit zone and dropped speed. Gen3 in such situation would get 6-8MPG more.

    It normally gets 58-60MPG in commute.
     
    #1 cyclopathic, Nov 17, 2015
  2. bisco

    bisco cookie crumbler

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    :(
     
    #2 bisco, Nov 17, 2015
  3. wjtracy

    wjtracy Senior Member

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    I've sometimes noticed a big step change in MPG after stopping for gaso on the highway. Never know if this is real or just the MFD. If it's real, could it be the stop puts us in a lower hybrid stage? Need to warm up and make a complete stop to get to final stage?
     
    #3 wjtracy, Nov 17, 2015
  4. cyclopathic

    cyclopathic Senior Member

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    I don't think it was the case. We only stopped to pump gas and make a quick run to bathroom. And it wasn't like it dropped and then climbed up, the average from the start was fluctuating btw low 38 to high 39 depending on slight incline. I-85 is very flat, ESP approaching Richmond, and there wasn't wind to speak of. I think C just not very aerodynamic
     
    #4 cyclopathic, Nov 17, 2015
  5. wjtracy

    wjtracy Senior Member

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    I-95?
     
    #5 wjtracy, Nov 17, 2015
  6. bisco

    bisco cookie crumbler

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    what is the c, .29 or something?
     
    #6 bisco, Nov 17, 2015
  7. Mendel Leisk

    Mendel Leisk Senior Member

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    73 mph is almost 120 kmh, that's getting up there, wind resistance becoming significant? I see on the Canadian highway Fuel Consumption ratings, Prius vs Prius c is 4.9 vs 5.1 liters per 100 km, which translates to 48 vs 46 mpg. Not a lot of difference, but some. The gas might also be a factor.
     
    #7 Mendel Leisk, Nov 17, 2015
  8. cyclopathic

    cyclopathic Senior Member

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    nope I-85, from Durham to Petersburg.
    Interstate 85 - Wikipedia, the free encyclopedia

    they (Toyota) say (lie?) .28, so 46 rating is very much inline with 48 of Gen3. Gen3 rated at .25, but also has bigger frontal area.
     
    #8 cyclopathic, Nov 17, 2015
  9. Andyprius1

    Andyprius1 Senior Member

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    probably just the colder morning temps now. 58-60 mpg at 73 MPH is quite good.
     
    #9 Andyprius1, Nov 17, 2015
  10. bisco

    bisco cookie crumbler

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    definitely not designed for highway speeds, but how many small commuter cars are?
     
    #10 bisco, Nov 17, 2015
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  11. cyclopathic

    cyclopathic Senior Member

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    Sorry for confusion I do not commute at 73MPH. Avg speed during commute in 35-40MPH range.

    In general C seems to be getting a better MPG than Gen3 at speeds <40MPH, and vice versa above.








    Funny you say it. Non-hybrid Mitsubishi Mirage is getting better than 38MPG at steady 73mph. To C's defense on 396mi tank there were 0.5mi of electric drive, just enough to cover getting in and out of gas station.
     
    #11 cyclopathic, Nov 17, 2015
  12. Mendel Leisk

    Mendel Leisk Senior Member

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    Yup. Not a big variation, a bit more significant on the highway:


    Capture.JPG

    (From Natural Resources Canada website, showing US mpg values)
     
    #12 Mendel Leisk, Nov 17, 2015
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  13. bisco

    bisco cookie crumbler

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    highway is the weakest part of any hybrid, imo. tough sell, if that's 99% of someone's driving.
     
    #13 bisco, Nov 17, 2015
  14. cyclopathic

    cyclopathic Senior Member

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    I am thinking there is something else going on, like with rear turbulence bubble or engine getting out of efficiency zone at that load. The MPG at 60-65MPH is much better, so despite this horrid stretch the overall MPG was 51.5MPG when we got back.

    The rear turbulence bubble is an issue with C, at steady 45MPH I've observed leaves being sucked in and staying there for many seconds.
     
    #14 cyclopathic, Nov 17, 2015
  15. Former Member 68813

    Former Member 68813 Senior Member

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    sounds like the MPG display error. what was the pump MPG?
     
    #15 Former Member 68813, Nov 17, 2015
  16. cyclopathic

    cyclopathic Senior Member

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    No I don't think so. Unlike Gen3 "C" has the "from the start", A-trip and B-trip MPG calculated, depending on if you are on A,B or odometer trip setting. And no "miles to empty".

    Turning ignition off resets "from the start" MPG.
     
    #16 cyclopathic, Nov 17, 2015
  17. Mendel Leisk

    Mendel Leisk Senior Member

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    This is a summary of the new Canadian "5-cycle" test, just the highway portion:

    Capture.JPG

    The top speed during testing is 97 km/h, about 60 mph, well below the 73 mph OP had his cruise set at. Miles per gallon tends to deteriorate logarithmically as speeds climb. Within the test parameters the c's mpg starts to lag, due to aerodynamic differences. Maybe the gap increases as speeds climb further?
     
    #17 Mendel Leisk, Nov 17, 2015
  18. GasperG

    GasperG Senior Member

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    #18 GasperG, Nov 17, 2015
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  19. davidc83

    davidc83 Member

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    You didn't buy this gas in Florida did you? Worst state in all my travels for mpg with their gas (I frequently travel 3-4 times a year from Indiana to Florida/Southeast). I bought my prius c 6 weeks ago in Florida and 2 days later traveled home to Indiana. As soon as I got on the Interstate I got 38mpg for that tank. However, after my next fill up in Georgia, bumped up to mid 40s and since I am averaging 48-50mpg. If you go to fuelly.com and search for Davidc83, you can see my 9 fill ups and the average mpg, with the first one being the worst. I know it was a brand new car and such, but I see the low bump on my other cars/motorcycles while traveling in Florida.
     
    #19 davidc83, Nov 18, 2015
  20. cyclopathic

    cyclopathic Senior Member

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    If you think Florida gas is bad, go to midwest. SD, MT, etc, especially if you buy off-brand. The E85 is incredibly cheap over there, so they cheat and dilute gas with it. I was there on motorcycle in 2008? and had to pull off highway to keep engine from overheating.

    No it is not gas it was Exxon station, and as soon as speed dropped to 62-63, MPG was ~53MPG.

    And my trip to work today was 50.8mi at 49mph with 60.4mpg, same gas
     
    #20 cyclopathic, Nov 18, 2015
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