1. Attachments are working again! Check out this thread for more details and to report any other bugs.

Major disparity in displayed mpg

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

  1. lochnersm

    lochnersm Junior Member

    Joined:
    Sep 25, 2020
    33
    9
    0
    Location:
    NJ
    Vehicle:
    2020 Prius Prime
    Model:
    XLE
    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.

    Posted via the PriusChat mobile app.
     
  2. Salamander_King

    Salamander_King Senior Member

    Joined:
    Nov 8, 2015
    10,985
    8,886
    0
    Location:
    New England
    Vehicle:
    Other Hybrid
    Model:
    N/A
    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

    Joined:
    Sep 25, 2020
    33
    9
    0
    Location:
    NJ
    Vehicle:
    2020 Prius Prime
    Model:
    XLE
    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?

    Posted via the PriusChat mobile app.
     
  4. Salamander_King

    Salamander_King Senior Member

    Joined:
    Nov 8, 2015
    10,985
    8,886
    0
    Location:
    New England
    Vehicle:
    Other Hybrid
    Model:
    N/A
    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

    Joined:
    Feb 24, 2016
    7,044
    7,587
    0
    Location:
    near Brisbane, Australia
    Vehicle:
    2016 Prius
    Model:
    N/A
    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

    Joined:
    Nov 8, 2015
    10,985
    8,886
    0
    Location:
    New England
    Vehicle:
    Other Hybrid
    Model:
    N/A
    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.
     
    jerrymildred likes this.
  7. lochnersm

    lochnersm Junior Member

    Joined:
    Sep 25, 2020
    33
    9
    0
    Location:
    NJ
    Vehicle:
    2020 Prius Prime
    Model:
    XLE
    Apologies. New to the app and prius community. I will try to do a better job of keeping it in the relevant threads.

    Posted via the PriusChat mobile app.
     
    Prodigyplace and Salamander_King like this.
  8. alanclarkeau

    alanclarkeau Senior Member

    Joined:
    Feb 24, 2016
    7,044
    7,587
    0
    Location:
    near Brisbane, Australia
    Vehicle:
    2016 Prius
    Model:
    N/A
    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.
     
    Salamander_King likes this.
  9. davran

    davran Member

    Joined:
    Mar 21, 2019
    99
    97
    0
    Location:
    BC, Canada
    Vehicle:
    2019 Prius
    Model:
    Base AWD-e
    Chiming in late.
    Two years of keeping a spreadsheet of mileage on my '19 awd-e has shown me that the dash mileage reading on mine is about 0.2 L/100kms or 2-us mpg optimistic.
    What I want to know is if I can change the L/100kms reading to two digits after the decimal, instead of just one.
     
  10. jerrymildred

    jerrymildred Senior Member

    Joined:
    Oct 28, 2016
    11,518
    14,127
    0
    Location:
    Tampa, FL
    Vehicle:
    2017 Prius
    Model:
    Two
    Not that I ever heard of. In my spreadsheet, I like to track the indicated mpg, but the stupid car (early 2017) won't show over 199.9 mpg. So, I switch to metric for that reading and convert. That told me in April, for example, that I got between 980 and 1568 mpg. Maybe just a little vague? A 0.1 resolution for L/100km is almost as dumb as a 199.9 mpg mpg limit.
     
    fuzzy1, krmcg and davran like this.