Better mileage when not in eco mode

Discussion in 'Prius v Fuel Economy' started by gone2green, Jan 9, 2018.

  1. gone2green

    gone2green grumpier than the grumpiest old man you know ;)

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    We traded in our 2007 prius for the 2015 prius v in July last year, and have noticed we get better mileage when the eco mode is off. Is that strange, normal, or what?
     
  2. Prodigyplace

    Prodigyplace Senior Member

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    Some people find driving mode affects mpg, others find it does not. My son, who has 2015 Prius v 5, thinks Eco mode on my Gen 4 is like PWR mode on the Prius v.
    I generally drive my Gen 4 in Normal mode (between Eco & PWR). I think my mpg may be slightly better because I do not need to push the accelerator as far.
    Some people here have tested the SmartPedal to improve mpg. It smooths out accelerator movement, removing movement due to road imperfections.

    SmartPedal | SmartPedal
     
  3. Aaron Vitolins

    Aaron Vitolins Senior Member

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    I noticed the same thing! I think the problem is that you would loose to much momentum while driving with eco and end up accelerating more than you would.

    And the V has so little power to work with, eco mode means pushing the peddle down a lot!
     
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  4. rdgrimes

    rdgrimes Senior Member

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    This is about throttle control and nothing else. (If your driving style lends itself to use of one mode or the other.) What gives you the best MPG is simply a matter of how much time/miles you spend in EV mode. So if you accelerate quickly and get into EV mode sooner you'll probably improve MPG. You can do the same thing in ECO mode, you just have to give it more pedal, which some people tend to resist doing.

    ECO mode actually offers you a greater energy savings due to several different functions, but if it causes you to stay out of EV mode more often, its not working for you.
     
  5. Mendel Leisk

    Mendel Leisk Lapsed Cargo Cultist

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    ECO Mode is a misnomer, for the most part. It apparently does some behind-the-scenes adjustments to AC performance, but it's main effect is to increase gas pedal travel. With our (regular) 3rd gen, I found the ECO pedal travel excessive, if anything, it was more difficult to modulate. "Normal" (neither ECO or PWR) has a nice linear feel, find by me.

    4th gen's have apparently shifted the gas pedal travel in the various modes, by roughly one mode towards more agressive? If so, then I'd likely prefer ECO in 4th gen. If I ever get there.
     
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  6. mikefocke

    mikefocke Prius v Three 2012, Avalon 2011

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    I thought that AUTO mode was what adjusted the HVAC.
     
  7. Prodigyplace

    Prodigyplace Senior Member

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    On Gen 3 (& prior?) the Drive Mode adjusts the HVAC to Eco. On Gen 4, you can also change the HVAC ECO mode separately.
    I drive in Normal Mode with ECO HVAC.
     
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  8. fuzzy1

    fuzzy1 Senior Member

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    Normal.

    Apart from some minor adjustments to ancillary systems (climate control, cruise control, engine auto-stop temperature thresholds), ECO / Normal / PWR modes are just different user interfaces at the gas pedal. Different 'touch and feel'. They have no impact on the actual propulsion system operation.

    An 'ideal' driver -- zero reaction time, infinite patience, perfect coordination and dexterity and foresight-- should be able to get the same results in all three modes. But when common human frailties are added in, then results diverge. Since different people have different driving styles and limitations, they will end up with different results and preferences.

    A plurality of drivers will get best MPG in ECO. Some (but fewer) will do better in Normal or PWR. And a few (but not many) will even be close enough to the ideal computer-like operator to achieve the same in all modes. Then others don't even care about any MPG differences, but go for seat-of-the-pants feel.

    Use whatever mode suits you best.
     
    #8 fuzzy1, Jan 9, 2018
    Last edited: Jan 9, 2018
  9. Mendel Leisk

    Mendel Leisk Lapsed Cargo Cultist

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    I'm really not sure about that, or at least: the variations are miniscule enough to be "lost in the noise". Especially between ECO and Normal, and more so if you rarely use AC.
     
  10. mikefocke

    mikefocke Prius v Three 2012, Avalon 2011

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    Never driven a Prius hatchback of any generation. I can only speak of my 5 years with a v and how the controls seem to work. On other versions of a Prius they may be different. In the first few months, I tried to learn what such a different car wanted, for the next few years, I tried to be conscious of what I did without being seen by any other driver as different. On a once a week 50 mile one way trip, I went from 65 in a 70 when I could without obstructing anyone to 68. Now I seem to be at 70 or maybe 72 but then traffic is heavier and it takes that to not obstruct. Or that is my rationalization. My MPG has suffered.
     
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  11. Mendel Leisk

    Mendel Leisk Lapsed Cargo Cultist

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    Kinda like trying to blend in with the walking dead...
     
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  12. GregC1979

    GregC1979 Junior Member

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    Here's mine, all in "Normal" mode. Same tank was 315 miles at exactly 1/2 tank.
     

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  13. taxibuddy

    taxibuddy Junior Member

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    Sorry to resurrect an old thread but I respectfully disagree with this. It makes logical sense to me that the best fuel economy should be achieved at a moderate constant speed where the engine is providing 100% of the required power. To put it in display terms, all red and no green.

    The green's purpose is to keep the engine in its most efficient operating regime, but anytime the green is use there is a price to pay in power conversion losses from the inverter and internal resistance losses from the battery. Avoiding these losses as much as possible improves fuel economy. (There is one exception of course. Friction losses are 100% so when faced with a choice of friction losses or electrical losses, take the electrical losses. That's a convoluted way to say avoid the friction brakes to the greatest extent possible.)

    The owner's manual clearly states that selecting EV mode on purpose will degrade fuel economy. The only time I ever use it is to reposition the car very short distances. In this case, it makes sense because for such a short trip the engine won't reach its efficient operating temperature anyway.

    As for ECO mode, it is based on one sound principle and one that is questionable. The sound principle is reducing the HVAC load. It's obvious on its face that any actual reduction in load will save fuel. The price you pay is less comfort. Of note: the HVAC intervention can be disabled. The questionable principle is changing the accelerator pedal feel. Most driver's will simply compensate for the less aggressive pedal by pressing the pedal harder which cancels any fuel savings. However, for an economy-minded driver, the less aggressive pedal MAY assist them in their efforts to save fuel by making it easier for them to drive gently.
     
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  14. TinyTim

    TinyTim Active Member

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    I spend way too much time behind the wheel analyzing my Prius and the various driving modes. You are better off driving a Gen 4 in normal mode vs. eco mode unless you pay close attention to your power band gauge. Eco mode is very touchy and if you go off EV mode on the flat. You have to let go of the accelerator and reapply power to re-enter EV mode. Eco mode does get better MPG if you focus on your driving and learn the Prius way in Eco mode. In normal mode the car goes into EV mode more. It's just my opinion but in Eco mode your prius will not go into EV mode using cruise control. Eco mode in cruise control has a main focus of regenerating power to the battery. In normal mode on cruise a Gen 4 Prius will cruise along in EV mode on the flat.

    For those who do not want to spend any time trying to get maximum fuel economy, Normal mode is your best bet.
     
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  15. Prodigyplace

    Prodigyplace Senior Member

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    I agree with your comments abut Gen 4, but this is a Prius v thread. There are no Gen 4 Prius v that I am aware of.
     
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  16. TinyTim

    TinyTim Active Member

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    My apologies. I was reading the (recent activity) thread and saw a lot of Gen 4 quotes in this thread. I did not realize this was a Prius V thread.
     
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  17. JimboPalmer

    JimboPalmer Friend to those who want no friends

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    If you are using cruise control, pedal mode makes no difference.
    Cruise control is better when it is completely flat and worse when it never is.
    if it gets hot enough, take it out of Eco so you can cool down.
    Every thing else is user preference.

    (I run Eco except summer afternoons)
     
  18. Mendel Leisk

    Mendel Leisk Lapsed Cargo Cultist

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    Using electric motivation in some degree to move the car is the cornerstone of the Prius. And it's replenishable: basically every time you're going faster than needed, touch the brakes, or even just coast, the car will recover some of that waste, store it in the battery.

    Constant speed, again, nope: all the scenarios where you're going to need to slow up ahead, for a red light, a corner, a danger, letting the speed fall-off, coasting, will use the car's momentum, let the engine shut down.
     
  19. taxibuddy

    taxibuddy Junior Member

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    All those round trips in and out of the battery are wasteful. They are double wasteful, actually. Losses going into and losses coming back out of the battery.

    I realize it is counterintuitive that engine-only represents the most efficient operating regime in any Prius without a plug, but it's true nonetheless.

    Clearly constant speed driving is impractical. Even on a test track, you have to accelerate from zero and return to zero. That's why the battery and MGs are there. They make the best of the those non-optimum situations.

    The point is that once you understand that constant speed, engine-only operations maximizes efficiency, you can let go of the idea of trying to maximize engine-off time. And again, the only exception is avoiding using the friction brakes to the greatest extent possible since friction braking is 100% wasteful.

    So let's look the case of having to come to a stop. What's the most optimal way of doing it? We already know we don't want to use the friction brakes, but we also don't want to regen either! Regen involves power conversion and a trip through the battery. Later we'll have to pull that energy back out of the battery and convert the power again. That's all wasteful.

    So if we're out driving constant speed on the test track and someone told use we had to stop, the the most efficient way is to operate the accelerator pedal so that it commands zero torque. That is, no motoring and no regen. We want to coast to a stop in the truest sense of the work. To coast in a Prius, you have to give it enough accelerator pedal to cancel the simulated compression braking regen that the controller adds for you. Doing this maximizes our rollout and avoids round trips through the battery and power conversion.

    I can already hear the objections that such driving is impossible and I agree. That's why the battery and MGs are thereā€”to handle the real world requirements.
     
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  20. mikefocke

    mikefocke Prius v Three 2012, Avalon 2011

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    I drive two main routes. One is a city route of maybe 5 miles each way. The other is a 45 miles each way. I drive in ECO 100% of the time. I see my v going into battery powered operation all the time depending on the terrain. As I go up a hill or accelerate, ICE. As I coast, battery. Maintaining a constant speed coming down even a gentle grade I use no gas.

    I don't baby the v, I stay up with or ahead of traffic. On the highway, I try to stay at or under the speed limit when no other cars are around. I use cruise control when I can. Once I get to 40 MPG, do I really care about the last 2%? I don't. I'm not out for bragging rights.
     
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