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Distance to empty number

Discussion in 'Gen 4 Prius Fuel Economy' started by dangrass, Jul 21, 2016.

  1. dangrass

    dangrass Junior Member

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    Still on the first tank with my 2016 2 Eco and was curious as to the remaining range number on the speedo display. The number I'm seeing seem way higher than it should be and I can't figure out how it's calculating the remaining range.

    For those who have more experience with this car, what's the deal with this number? Is it actually right? Is it calculated based on the very most recent mileage?

    thx,
     
    #1 dangrass, Jul 21, 2016
  2. Mendel Leisk

    Mendel Leisk Senior Member

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    How many pips showing on the fuel gauge? Are you seeing a correlation?
     
    #2 Mendel Leisk, Jul 21, 2016
  3. dangrass

    dangrass Junior Member

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    Currently it has 3 and a third pips. The number is getting lower as the tank is getting drained. Currently says that the car has 331 miles of range and it's got 424 on the tank so far. According to the computer the mileage since new is a tad under 61. If that gauge is linear 3 and 1/3 pips should be about 4.75 gallons remaining in the tank. For the car to go 331 miles on this it would need to be getting 69.68 mpg....which is more than it's getting. Does the car have reason to believe that we will be traveling mostly downhill in the near future? Is the fuel gauge pessimistic? Something else?
     
    #3 dangrass, Jul 21, 2016
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  4. Mendel Leisk

    Mendel Leisk Senior Member

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    Could be first tank machinations, something got reset by dealership. It does sound you're on top of it.
     
    #4 Mendel Leisk, Jul 21, 2016
  5. dangrass

    dangrass Junior Member

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    Thx. Is the fuel gauge on these cars linear? Is it reasonable for me to assume that 3.33 pips (42% of a tank) = 11.4 x .42 = 4.75 gallons?
     
    #5 dangrass, Jul 21, 2016
  6. alanclarkeau

    alanclarkeau Senior Member

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    If this is your first tank, fill it up now and start afresh with a full tank. First tank on any of my last 3 cars never seems to get it right until it is topped up. It seems to work on an algorithm based on your recent driving, but I've never quite worked out how it does it.
     
    #6 alanclarkeau, Jul 21, 2016
  7. dangrass

    dangrass Junior Member

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    Ok, thx.
     
    #7 dangrass, Jul 21, 2016
  8. Mendel Leisk

    Mendel Leisk Senior Member

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    On 3rd gen all the gas gauge pips seem to show for quite sometime. Once they start disappearing its more linear.
     
    #8 Mendel Leisk, Jul 21, 2016
  9. dorunron

    dorunron Senior Member

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    It would be best to go by the fuel gage and only use the DTE for a reference.
     
    #9 dorunron, Jul 21, 2016
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  10. bwilson4web

    bwilson4web BMW i3 and Model 3

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    Trust nothing until running the tank dry with a spare, 1 gallon can of gas.

    Bob Wilson
     
    #10 bwilson4web, Jul 21, 2016
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  11. bisco

    bisco cookie crumbler

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    the pip is quite linear, with 8 bars and almost exactly 1 gallon/bar. the dte follows along quite nicely, based on past performance.
     
    #11 bisco, Jul 21, 2016
  12. fuzzy1

    fuzzy1 Senior Member

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    Linear? My Gen3 gauge is more linear than any previous car, but still not fully linear. Note that from engineering and mathematical viewpoints, linearity refers only to the amount of fuel between each division or mark.

    Like all before it, the top of the gauge is not at the top of the tank, and the bottom of the gauge is not at the bottom of the tank. These are gauge offsets, separate issues than linearity. Most cars have some safety margin or reserve below the Empty or Zero point of the gauge. However, my first car was one of the exceptions, running out while the gauge still showed more fuel remaining. That is one of the reasons for testing the low fuel regions of my cars. If I've never used it, then I don't assume it is there for future emergency.

    No. The offsets wreck that computation.

    Read the first post of this long thread for fuel safety margin guidelines on the Gen3. I'm not aware of anyone yet doing this test on the Gen4, but several hints suggests that it is roughly similar.
    [WARNING] Running out of gas (Gen III) | PriusChat
     
    #12 fuzzy1, Jul 21, 2016
    Last edited: Jul 21, 2016
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  13. Mendel Leisk

    Mendel Leisk Senior Member

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    This is the old "how low can I go", in fact it feels old hat just saying this. My dad used to use a stick to check the gas level on our Beetle, pretty reliable.
     
    #13 Mendel Leisk, Jul 21, 2016
    Last edited: Jul 22, 2016
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  14. krmcg

    krmcg Lowered Blizzard Pearl Beauty

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    I have noticed that the DTE reaches "0" pretty much at the estimated point (adding the DTE number and the current tank mileage from a tank that is at least half gone). The gas light comes on by average 30 - 32 miles before that point. The average for me in 15 fillups are light comes on at 630 miles - DTE reaches "0" at 661 miles.
     
    #14 krmcg, Jul 22, 2016
  15. pakitt

    pakitt Senior Member

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    I am checking how the DTE is working and will report when I am finished with my 3rd tank. So far it seems just as useless as Gen3 was. And the fuel light comes up too conservatively (like with almost 7-10L of fuel still inside)....More data needed.
     
    #15 pakitt, Jul 26, 2016
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