Let's have an honest top 20 fuel efficiency, seperate EV and HV

Discussion in 'Gen 1 Prius Plug-in 2012-2015' started by Jerry Liebler, Oct 31, 2014.

  1. Jerry Liebler

    Jerry Liebler Member

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    The fact is the PIP uses 2 fuels with dramatically different results. The EPA recognized this and gave an HV rating that corresponds to driving without pluging in and a separate rating for "blended" operation after charging. The EPA also noted the conditions of the blend which show 90% EV. From the EPA blended data and the 50MPG combined rating and that the EPA achieved 105MPGE on their EV miles. Since the EV ratio varies from time to time for any PIP comparisons over time need to track gas MPG and EV MPGE separately. recording and resting one of the ratio screens at each fill up along with the odometer distance since last fill up and pump gallons are all that is needed to compute HV MPG and EV MPGE. Some PIP owners on "FUELLY" have included the ratio data as notes on their logs which allows calculation of both numbers but it seems that all fudge the result either by reporting "blended" MPGE or even worse ignoring the electrical fuel entirely and reporting outrageous MPG.. In my mind the only honest way to report on FUELLY is to report HV MPG which would be quite comparable to the data for the rest of the Prius family of cars. I calculated the HV MPG of one tank, shown on FUELLY, at 37.17MPG yet it was reported as 306.7MPG by dividing total miles by gallons used, completely ignoring the electrical power used which resulted in 142 MPGE for the EV portion or an actual blended 106 MPGE.
    We have the EPA benchmarks, 105 MPGE for EV and 50 MPG for HV . We can easily compare our results to each of these results separately and compute a weighted average by using that tank's ratio of EV to HV and multiply by the 95 MPGE EPA rating to have a much more valid idea of how we are doing. Even the weighted average biases the results by strongly favoring a high ratio of EV to HV so it really would be better to rank EV MPG and HV MPGE independently.
     
  2. CaliforniaBear

    CaliforniaBear Clearwater Blue Metallic

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    Just drive the car and enjoy the good mileage. Or participate in the complete spreadsheet already established. PIP & MPG Spreadsheet | PriusChat Or simply track gas and electricity use and use the EPA formula 33.7 kWh equals 1 gallon of gas.

    Also Note: EV miles that you went because the battery was nicely charged stopping or going down hills don't have an equivalent "cost" in electricity from the power company or measurable gas that got you up the hill or maybe up to speed before braking.
     
    #2 CaliforniaBear, Oct 31, 2014
    Last edited: Nov 1, 2014
  3. Mendel Leisk

    Mendel Leisk Senior Member

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    Fuelly should really separate out the PIP, it's definitely in another league. To lump them all together just muddies the waters. But I guess here is not the place to be accomplishing that. Does Fuelly have avenues for feedback, sorry I haven't checked.
     
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  4. bisco

    bisco cookie crumbler

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    jerry, can you use my spreadsheet info, or is there something more that you need me to report? thanks!
     
  5. shiranpuri

    shiranpuri Junior Member

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    Tracking dual power isn't simple - if I always use HV uphill and EV downhill, my EV numbers would be good, but my HV numbers would be low.
    If I do the reverse, the reverse would apply. If I live just within range, and sometimes make it home fully on EV, and sometimes pull in shortly after the engine started - HV would look horrible, where it's not being used much.

    Actually, tracking consumption rate/efficiency in and of itself is not simple. Suppose I get 50 MPG on a 40 mile commute (keep charging out of it for simplicity). Now suppose I were to move 20 miles closer, and end up with 45 MPG on a 20 mile commute instead. Did efficiency go up or down? It went from .8 gallons/commute to .44 gallons/commute.

    Point being, there's still more to the story, and different people will harp over different numbers.
     
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  6. Jerry Liebler

    Jerry Liebler Member

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    Actually the spread sheet gathers too much data and some of it is sadly misleading. Columns: C, D, H & L are all that is needed as input per "fill-up". The formulas become (C-L)/D=MPG on gas, L/H/33.7/0.85= MPGE on electricity.
    L/C*100% = %EV, (C-L)/C*100% =%HV, MPG on gas/50MPG=HVFACTOR, MPGE on electricity/105=EVFACTOR, (EVFACTOR*%EV/100%+HVFACTOR*%HV/100%)*95MPGE=SCORE.

    SCORE is an equivalent that shows how this trip compares to the EPA combined result.

    The weighted average "SCORE" ( defined in my last post) does a good job of removing the advantage of high ratio of EV to HV while retaining the appearance of a fuel economy # and would be a useful way of comparing EV vs HV usage strategies. A more conventional score, more like what we got in school, would substitute 100% for the 95MPGE in the last formula of my last post
     
  7. bisco

    bisco cookie crumbler

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    excellent. so how are we going to go about this?
     
  8. Jerry Liebler

    Jerry Liebler Member

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    Unfortunately, I and probably most PIP pilots haven't kept enough records to go back in time very far. I really only have adequete data for my last fuel up, but I'll be gathering it from now on.
    If the "spreadsheet" has capabilities similar to "Exel", the custodian of the "spreadsheet" could enter the formulas for new columns then sort rows to generate peer rankings on say MPG, MPGE, & SCORE.

    And, I've got to figure out how to enter data into the "spreadsheet".
     
  9. bisco

    bisco cookie crumbler

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    it's easy, even for me. you add your data to the 'add data here' page, and then pm ken aka ukr2 and he'll move it into the main body. i'm sure he can add whatever formula's are necessary.
     
  10. Jerry Liebler

    Jerry Liebler Member

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    Bisco,
    My data should appear whenever Ken chooses. Now that I've figured out how to access the spreadsheet and scanned it's contents I've asked KEN to change the labels of columns R,T, and U as they are what I would call EV MPGE, HV MPG, and Blended MPGE.
    BTW your data says you are an outstanding hypermiler or must drive quite slowly.
     
  11. bisco

    bisco cookie crumbler

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    sit low and drive slow, 23mph average.:eek:
     
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  12. markabele

    markabele owner of PiP, then Leaf, then Model 3

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    Also, please post a picture of your ratio screen and submit it to the Top 20 MPGe thread.
     
  13. Jerry Liebler

    Jerry Liebler Member

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    I'll never make that top 20 simply because of it's bias toward EV. On my best tank I might get 20% EV. I drive mostly 55 mph hilly 2 lane (can't block traffic) roads and still manage to better the EPA ratings by 10% or more. I reset trip A on each tank and typically see average speeds on it of 40 to 50 MPH.
     
    #13 Jerry Liebler, Nov 2, 2014
    Last edited: Nov 2, 2014
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  14. SageBrush

    SageBrush Senior Member

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    ... that you have posted a wall of text that I cannot understand.

    Perhaps start here:
    1. Define efficiency as an engineering term
    2. Distinguish MPGe from source energy consumption per mile.
     
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  15. retired4999

    retired4999 Prius driver since 2005

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    That's what we do!
    (y)
     
  16. Jerry Liebler

    Jerry Liebler Member

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    Efficiency is not discussed, in any way, so no need to define it!
    MPGE is, in effect, defined by the EPA as miles/33,700 watts entering the car. Source energy is irrelevant for this discussion!
     
  17. SageBrush

    SageBrush Senior Member

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    Let me remind you of your title: Let's have an honest top 20 fuel efficiency, seperate EV and HV

    As for MPGe, you have the ratio reversed. I'm really not trying to badger you, I don't understand what you want.
     
  18. slcMPG

    slcMPG Member

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    The top 20 MPGe (which I am #11) does seem to be a top EV contest.

    I think it would be cool to have a post of top MPG on trips greater than 60 miles (or some high miles) with a single charge. Just the other day I did 60 miles at 79 mpg.

    Other wise like people are saying you can easily game one power mode to boost the other.
     
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  19. Jerry Liebler

    Jerry Liebler Member

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    The spread sheet has the new column with %EPA in column X so we can all see where we rank against the EPA data.
    Speed kills fuel economy for either fuel, those who average lower speeds still have an advantage and Bisco is definitely the slowest, at least on the spreadsheet, averaging a remarkable 150% of benchmark I'll wager Pluggable rarely cruises freeways as he is clearly second at something like 140% of benchmark. My one tank entry puts me about 19th with my paltry 111.7%. I'll just have to slow down some.
     
  20. bisco

    bisco cookie crumbler

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    a column for average mph per tank would be fun.
     
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