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Using Neutral?

Discussion in 'Gen 1 Prius Plug-in 2012-2015' started by Gaudete, Feb 1, 2013.

  1. Gaudete

    Gaudete Junior Member

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    Posts on hyper-miling suggest shifting one's car into neutral to coast as frictionlessly as possible on little gas. The method works - I've used it effectively with my '94 Chevy.

    But with the prius, putting the car into neutral eliminates the ability to recharge the battery via regenerative breaking (which seems to kick in as soon as you take your foot off the acceleration in Drive).

    So what makes the most sense from a fuel economy perspective?
     
  2. retired4999

    retired4999 Prius driver since 2005

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    Rolling freely is better than regenerating, but if you have to brake make sure your back regenerating.
     
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  3. Gaudete

    Gaudete Junior Member

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    Thanks. Back regenerating means the "B" gear, correct?
    Are there speeds at which that's not good for the car (such as going downhill at 60 mph)?
     
  4. retired4999

    retired4999 Prius driver since 2005

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    No, B is for engine braking when going down steep hills to slow car. For normal driving just leave car in D. When you want to coast just lift your foot slightly and keep it rolling with out gas and without regeneration. Then when you stop you will be regenerating, then you will be ready to go again just give it gas and go.
     
  5. retired4999

    retired4999 Prius driver since 2005

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  6. bisco

    bisco cookie crumbler

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    keep the bar on the hsi at or just to the right of regen. that's close enough to coasting for true hypermilers. that way, when you want to slow down, you can just let off the pedal a bit and regen, instead of trying to switch from neutral to drive and calibrate your foot as well.
     
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  7. jmlarence

    jmlarence New Member

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    Gliding in neutral should be part of the "learn to drive the PIP manual." This car rolls forever. I'll build up speed in neutral just to gain breaking regen. Shifting from "D" to "N" is like cutting the cord. I often wonder how much the regen brakes and transmission hurts MPG.
     
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  8. mmmodem

    mmmodem Senior Taste Tester

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    +1 What he said. Also check out this video.
    Prius MAX MPG Secrets - YouTube
     
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  9. drysider

    drysider Active Member

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    If you are building up speed in neutral, then you are going downhill and should be charging the battery. The regen system is responsible for approximately 1/3 of the Prius overall mileage efficiency. Shifting to neutral does a lot more than just disable the regen. You should probably be wondering how much better your mileage would be if you let the hybrid system do its job.
     
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  10. Gaudete

    Gaudete Junior Member

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    That is precisely my question !
     
  11. bisco

    bisco cookie crumbler

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    and it's answered in post #6. don't bother with neutral, just drive it.
     
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  12. CharlesH

    CharlesH CA HOV Decal #5 on former PiP

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    And at the risk of sounding like a wuss, coasting in Neutral is a vehicle code violation in some states, such as California.
     
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  13. Mendel Leisk

    Mendel Leisk EGR Fanatic

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    With the Prius at least, I'd leave it in Drive, all the time.

    B mode (increased engine braking) is worthwhile only if you're running down an extremely long/steep hill, to the point that the battery will not charge any more and the car switches over to regular brakes, and they start to overheat.

    I don't think I've had the experience. I recall rolling into Whistler from the east, a very long downhill run. Thought I'd try B mode. Engine revs shot up, alarmingly. I switched back to drive, revs went down, and the car continued to charge.

    Even if you do exceed the charging limit, I've heard the car will do a bit of B mode, without you even selecting it.

    And shifting to Neutral seems to make little different to rolling resistance in my experience. Plus no charging.
     
  14. Gaudete

    Gaudete Junior Member

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    Thanks for all the advice. I think I'm going to experiment with Neutral. Unless I'm looking to slowly and gradually decelerate, I'm going to put the car in Neutral and coast with as little resistance as possible. I understand that doing this is the same as hitting the acceleration pedal ever-so-slightly, but I actually find that more difficult (and uncomfortable) than simply going into neutral. I'm used to driving this way (that is, shifting between neutral and drive), and am happy to go back to it. If I notice anything appreciable in terms of fuel efficiency, I'll report back.
     
  15. mmmodem

    mmmodem Senior Taste Tester

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    Wow, going against a unanimous group of replies. You've got some nerve... Just kidding. I'm on the other side but good luck all the same.
     
  16. bisco

    bisco cookie crumbler

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    experimentation is fun, and always a learning experience.:)
     
  17. lensovet

    lensovet former BP Brigade 207

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    To those saying it's bad because it doesn't charge: consider this.
    In D, when you let off the accelerator, the car starts doing the equivalent of engine braking, but with regen. That means it slows the car down more so than if you just coasted. Now, if you wanted to maintain speed instead of slowing down, you'll have to speed up again. Given the laws of physics, it should be obvious that regen+reaccelerate is going to be less efficient than just straight up coasting.
     
  18. mmmodem

    mmmodem Senior Taste Tester

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    Agreed...except on a hybrid the ICE shuts off when power demand is low. Hardcore tactics for pulse and glide involve an engine kill switch in combination with neutral. The Prius may or may not turn off the ICE depending on conditions when neutral was triggered.
     
  19. bisco

    bisco cookie crumbler

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    actually, when you let off the accelerator all the way. when you let off partially, you can glide just like in neutral.
     
  20. Mendel Leisk

    Mendel Leisk EGR Fanatic

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    Yeah. I hadn't really thought about, but I think I do sometimes subconciously ride the gas pedal slightly, for a better coast, preventing charging. IMHO, that's easier and more convenient than shifting to Neutral.