Major disparity in displayed mpg

Discussion in 'Gen 4 Prius Fuel Economy' started by Jbania, Oct 18, 2020.

  1. lochnersm

    lochnersm Junior Member

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    Is there a way to figure out how many miles were accumulated in hv mode so far? I think I can get a decent estimate of gallons of gas. My trip B has never been reset and says 81% of EV, but I think that includes when HV goes into EV, correct? Because if I use my estimate, my mpg is closer to 33, and that seems ridiculously low.

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  2. Salamander_King

    Salamander_King Senior Member

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    Correct.

    The short answer is, there is no direct display of HV mode only miles or mileage on PP. However, there are several ways to estimate the HV mode only mpg. One is if you know the total kWh you have used from the wall to charge the traction battery as well as the total gas used. Making several assumptions, you can extrapolate the HV mode only mpg like I showed on my earlier comment #19.

    If you have not logged your total kWh used, then easier way is use DTE display right after you refuel the tank to full. The DTE is a distance to empty displayed. If you divide this number by 9.3, you will get rough estimation of what mpg the HV portion (gasoline only drive) was from the previous tank. See this thread for more explanation: What is your DTE after fill-up? | PriusChat
     
  3. lochnersm

    lochnersm Junior Member

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    I see how you are doing your math, but how did you determine 9.3 is your factor? Is that the amount of fuel needed to fill up once DTE has reached 0?

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  4. Salamander_King

    Salamander_King Senior Member

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    Yes. The tank size is 11.3gal, but the gas empty light comes on ~2gal before completely empty. This is when DTE reaches 0.
     
  5. alanclarkeau

    alanclarkeau Senior Member

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    Isn't it shown if you select ODOMETER?

    Last I looked at my PRIUS, it shows 28%EV - and 4.0 l/100km - on the ODOMETER.

    So I suppose that means that the ICE was using 5.6 l/100km WHILE IT WAS ACTUALLY WORKING. And the HYBRID Battery used 0 l/100 while it was driving. 5.5 is still better than a non-hybrid ICE.

    Not sure how to work that out on a PRIME?
     
  6. Salamander_King

    Salamander_King Senior Member

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    He (@lochnersm) is asking about his Prius Prime. Yeah, I understand this is Gen4 thread. But for PP, the mpg displayed includes the distance driven in EV mode from the wall charge. That makes displayed mpg totally useless unless one is driving a PP solely on HV mode without doing any charging. To make things more complicated, the EV ratio displayed is not solely on EV mode drive from the charge, but also includes the EV portion of the HV mode. This makes a straight calculation of real HV mode mpg impossible.
     
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  7. lochnersm

    lochnersm Junior Member

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    Apologies. New to the app and prius community. I will try to do a better job of keeping it in the relevant threads.

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  8. alanclarkeau

    alanclarkeau Senior Member

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    Yeah - I thought that was probably the case.

    A bit like why WLTP is so confusing to most people (and easy to be deceptive or outright devious if the salesperson wants it to be).

    Hence my last sentence.
     
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