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All EV drive does not mean 100 MPG?

Discussion in 'Gen 3 Prius Fuel Economy' started by Roger T, Mar 2, 2014.

  1. Roger T

    Roger T Member

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    I bought my prius a month ago. Still practicing some high MPG techniques.

    I notice something really interesting. I was driving in the city and i keep my speed under 30 mph. Sometimes even if i keep the energy indicator on the left side of medium line (which means all EV driving, exactly like the attached picture), the instantaneous MPG indicator will not always rise to highest, instead, it was about 40 or 50 mpg.

    Since it is all EV driving, i suppose the instantaneous MPG will be 100 MPG all the time. But it sometimes drop to 40 or 50 mpg on the instantaneous MPG indicator.
    Hope to hear what you guys think. :) Prius-PHV_EcoMeter-EV-in-HV_Green-02.jpg
     
  2. fuzzy1

    fuzzy1 Senior Member

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    Is the ICE fully warmed up and not running? If it is running to provide engine heat, cabin heat, catalyst heat, or traction battery recharge, you won't be getting 100 mpg.
     
  3. Roger T

    Roger T Member

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    It turns out it is the heat. I was not aware of that... Thanks a lot for your reply.
     
  4. bisco

    bisco cookie crumbler

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    you would have to wait until the ice shuts down, then reset the meter.
     
  5. Roger T

    Roger T Member

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    I notice that when I reset the trip stats after the ICE preheats... I got 99.9 MPG as long as i maintain the all electric drive! Interesting.
     
  6. bisco

    bisco cookie crumbler

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    exactly.;)
     
  7. jdk2

    jdk2 Active Member

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    And as soon as you deplete the HV battery, the ICE will restart and you loose the MPG from all that EV running to recharge the battery. Use EV wisely as there's no free ride. That energy has to come from some place.
     
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  8. Roger T

    Roger T Member

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    Totally. It seems that even I use the all EV as much as possible, I did not notice much of the battery depletion. It depends on the road condition. The battery will be recharged from my other non-all EV drive and regenerative braking.
     
  9. bwilson4web

    bwilson4web BMW i3 and Model 3

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    Hi Roger,
    Sad to say, the existing Prius instrumentation does not give a very accurate picture of what is going on. I would suggest getting a Scangauge II or equivalent that gives better metrics about what the Prius systems are doing.

    When doing your research, make sure the one you choose can read out the traction battery metrics as well as error codes. The Scangauge community is used to putting in XGAUGE definitions to expand the scope. But other OBD scanners may have similar capabilities. Having the ability to record the data is a definitely a plus.

    Bob Wilson
     
  10. Roger T

    Roger T Member

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    Thanks Bob for your suggestion. For now i think the Prius onboard instruments are enough... May look into Scangauge in the future tho.
     
  11. kensiko

    kensiko Member

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    The outside temperature and inside heating really hit the MPG. I could not do better than 6 L/100 km (39 mpg) during cold days this winter (below -20 Celcius).

    Capture Fuelly 2014-03-07.JPG
     
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  12. bisco

    bisco cookie crumbler

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    it all depends on your trip distances. i was able to accomplish well over 40mpg on trips beyond 3 miles, even in the polar vortex.
     
  13. css28

    css28 Senior Member

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    It's misleading you though, because you burned gasoline to put that charge in the battery and you *will* have to make up what you've used by burning gasoline. It wasn't free.

    For moving around at 25 mph hour for shorter distances the EV mode makes some sense (the ICE simply doesn't run efficiently at very low power levels).

    Consciously holding the HSI below the midpoint for most driving, while cool, isn't really saving anything in the long run.
     
  14. retired4999

    retired4999 Prius driver since 2005

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  15. Roger T

    Roger T Member

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    Agree. It will make more senses if I am driving the plugin prius.
     
  16. Roger T

    Roger T Member

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    retired4999 likes this.
  17. css28

    css28 Senior Member

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    Now if you want a thrill, test drive a Volt.

    Unlike a plug-in hybrid it's truly an electric car. What's the difference you ask? It's maximum acceleration (pedal to the floor) is purely electric, with no chance of the engine kicking in to help.

    We still have our Prius but my daily driver since last summer is a Chevrolet Volt.
     
  18. dorunron

    dorunron Senior Member

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    Roger T, remember that the Prius has to get into the fully warmed up situation before it will show 99.9 in EV mode. This is commonly referred to as S4 mode.

    Once you get into the S4 mode, the Prius will then show the 99.9 whenever you are not using the ICE.

    This is explained in detail in the following link. Even though the data is for the older generations, (Gen I and Gen II), it still basically works the same way in Gen III.

    http://techno-fandom.org/~hobbit/cars/five-stages.txt

    Hope this helps and best of luck to you!
     
  19. KennyGS

    KennyGS Senior Member

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    [​IMG]

    I notice the Volt's est fuel economy figures are lower than the Prius.
     
  20. xraydoug

    xraydoug Active Member

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    on the prius c, there is a regen/eco/power bar that also indicates if the car is on EV. the mpg listed is selectable to one of three odometer settings. since car is started, trip A, trip B. by using this screen and set to since started the mpg will be low while the engine warms up. then after a miniute it will go to EV at slow speed and the mpg will start climbing. by using this screen the car takes into account the gas burned since warm up. or trip A or B. This setting gives me a better understanding of my mpg since start/for the tank(I use trip B)/since bought the car(trip A)