When Does Gas Kick In?

Discussion in 'Gen 4 Prius Fuel Economy' started by PriusPeep, Oct 31, 2017.

  1. PriusPeep

    PriusPeep Member

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    I was re-reading Consumer Report's review of the Gen 4 Prius. Here's what they say about staying on electric power:

    As before, the Prius can propel itself on electric power alone at low speeds and with a light foot, typically up to 40 mph if you're patient. That's handy in stop-and-go traffic or when you're just loafing along on Main Street.

    I've read elsewhere that you can stay on electric up to about 25-27 mph.

    I was looking for the answer in the manual and could not find it.

    Is there a definitive answer?
     
  2. fuzzy1

    fuzzy1 Senior Member

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    Was 'elsewhere' referring very specifically to Gen4? Or possibly to Gen3, for which that speed is approximately correct?
     
  3. bisco

    bisco cookie crumbler

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    should be in the manual, have you tried it? i thought 60 mph or better.
     
  4. Prodigyplace

    Prodigyplace Senior Member

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    From a stop with straight EV the engine cuts in at 20 mph until it warms up. The car periodically uses EV up to about 60 mph IIRC.
     
  5. RCO

    RCO Senior Member

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    Mine will switch to EV under ideal conditions on motorways (like intestate) at more than 70 mph.

    To infinity and beyond.....!
     
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  6. Prodigyplace

    Prodigyplace Senior Member

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    I hope you meant interstate LOL

    in·tes·tate
    inˈtestāt,inˈtestət/
    adjective
    1. 1.
      not having made a will before one dies.
      "he died intestate"
    noun
    1. 1.
      a person who has died without having made a will.
     
    #6 Prodigyplace, Nov 1, 2017
    Last edited: Nov 1, 2017
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  7. Mendel Leisk

    Mendel Leisk Senior Member

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    It's more than 40 mph, that's the cut-off for third gen. I know on ours (3rd gen), there's a long steep downhill where I'm accelerating, and I can see/feel the engine kick in around 72 kmh (~45 mph), guaranteed.

    I've seen documentation for the similar but higher threshold on 4th gen, it's significantly higher. But maddeningly elusive this morning, not sure why.

    I've looked through my 2016 Prius Owner's Manual pdf, and this 2016 Toyota Prius Press Release document. I though the latter would have something, but I'm not finding it. I'm sure the info is out there though, in some sort of "white paper".
     

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  8. first_superior_prius

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    There might be a definitive answer... but the practical answer is "it depends" from my observations

    Depends on if the ICE is warmed up. Depends on how fast you accelerate. Depends on level of battery charge. Depends on ambient temp (relating to ICE warmed up and battery charge). Depends if you have AC or heat cranked.

    EV mode will kick on for me up to mid 60s if I'm driving on flat ground on the highway and not accelerating. If I am going over 70 it does not kick on full EV mode.

    Typically from a dead stop, if I am accelerating slowly, it stays on until high 20s/low 30s, but it varies a lot due to the aforementioned variables
     
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  9. RCO

    RCO Senior Member

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    You may think that, I couldn't possibly comment! (Asside: B*gger! This auto correct will be the death of me)!
     
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  10. PriusPeep

    PriusPeep Member

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    I was referring to Gen 4. I wrote "elsewhere" because I couldn't remember where.

    When I was at Barnes and Noble this week I remembered that it was in another Consumer Reports publication. Their annual car buyer's guide with the brief reviews says that it stays in EV up to about 25 mph. Obviously that's different from the quote I posted from CR's full review that's available to subscribers.

    I went back again and spent about 30 min reading through by 2017 owner's manual. I was sure I'd previously read that information in that book. But I could not find it.

    After a year with my Prius, I cannot distinguish when it shifts to gas.

    Incidentally, I find my dealer unwilling and/or unable to answer many basic questions about my Prius.
     
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  11. RCO

    RCO Senior Member

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    Sadly there are far too many Toyota sales guys who don't really have a clue about the Prius. It's rare to find one who knows the details.
     
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  12. mmmodem

    mmmodem Taste Tester

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    Wow, on our second year of a Gen 4 and we still don't know? On a Gen 3, it's 42-46 mph. If slowing down, it's 42, speeding up it's 46. I would expect the Gen 4 to be at least this but I don't know.

    On a PiP with EV remaining, it's 62-65.

    And bonus, it's 82-84 for ECO. If you exceed 84 mph, the ECO light turns off. (Not to be confused with the ECO button)
     
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  13. The Electric Me

    The Electric Me Go Speed Go!

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    Since I no longer own a Prius, I'd say The Gas kicks in about 2-3 hours after eating the vegetables or burrito.
     
  14. Kiril

    Kiril Junior Member

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    There is no speed limit on electric power. However there is output power limit and I believe the limit is placed well below the maximum output of the electric motor as the battery is not too big in the regular Prius. So if you look at the dash there is an initial interval of the output torque where you can benefit from electric only. If you step on the gas firm enough to demand more torque the gas engine will kick in possibly aided by the electric one.....

    If you keep the torque in the EV sector and battery is not empty and car is not cold - you are going all electric.....

    [​IMG]
     
  15. kevinwhite

    kevinwhite Active Member

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    The Gen4 limit for running in EV mode is 68mph - this is about 110km/h. Beyond that speed MG1 would exceed it's 17,000 RPM limit.

    kevin
     
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  16. Prodigyplace

    Prodigyplace Senior Member

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    Don't you mean MG2?
    MG1 at that point would be charging the battery if the engine is running.
     
  17. kevinwhite

    kevinwhite Active Member

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    No - MG1 is the one driven from the sun gear. MG2 is the larger one driving the ring gear and final drive. Its RPM just depends upon road speed - the nomenclature always seems wrong to me.

    In EV mode the ICE is not rotating so MG1 has to rotate backwards at a speed proportional to the road speed. In the Prime the one way clutch enforces the stationery ICE so that MG1 can provide additional tractive effort. This is not possible in the normal hybrid.

    Actually I've found a reference that the maximum EV speed in the Prius Prime is 135km/h and as far as I can see the gear ratios are identical to the normal Gen4 hybrid.

    So the normal hybrid may have a theoretical limit of ~84mph. Although I've seen references to 68mph as being the limit and my experience seems to be consistent with that.

    kevin

    [​IMG]
     
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  18. RCO

    RCO Senior Member

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    Makes sense, but I have certainly seen mine in EV at over 70mph on a motorway!

    135kph is the max for EV as quoted above and that equates to 83.885mph
     
  19. Prodigyplace

    Prodigyplace Senior Member

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    That quote was for the Prime.
    The Prime has an added one-way clutch that we do not have in Gen 4.
     
  20. kevinwhite

    kevinwhite Active Member

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    Agreed but that doesn't change the basic operation - it just allows MG1 to provide additional tractive effort with the ICE remaining at zero RPM. It doesn't affect the speed of MG1.

    Also as I mentioned it looks like the Prime and normal hybrid have identical gearing.

    kevin
     
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