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Glide vs coast?

Discussion in 'Prius c Main Forum' started by MsTee, Mar 1, 2017.

  1. MsTee

    MsTee Junior Member

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    I'm a newbie and have a silly question that I hope someone here can answer. Is gliding different to coasting? I understand the pulse part, it's the glide part that confuses me.

    I think of coasting as just letting the car go without pressing my foot on the accelerator. (In an old car, I'd even take the car out of gear to coast.) When I read this forum I saw this comment:

    Fuel economy short-path zen:
    • - Gliding (lightly pressing the gas pedal so that no arrows point into or out of the battery on the "Energy" display) is better than coasting
    • - Coasting (foot off the gas pedal) is better than braking
    • - Braking is better than stopping
    From <What every newb should know | PriusChat>

    Then, looking elsewhere on the web, I see that some people talk about the glide as if it's the same as coasting, to the extent that they talk about putting the car in neutral.

    I figured the above comment is the right one. Gliding is different to coasting. In a glide you just take the pressure off the accelerator but don't remove pressure completely. Am I correct?
     
  2. Sam Spade

    Sam Spade Senior Member

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    You will be the happiest with your new car if.........you just DRIVE it, using some common sense and not worrying about all of this hyper-milling crap.

    Your attention should be on the road and traffic conditions around you. Getting an extra .5 MPG will be pretty meaningless if your brain is tied up worrying about THAT and you crash into something. :eek:
     
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  3. jerrymildred

    jerrymildred Senior Member

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    I think @Sam Spade is right, but to answer your question, you take your foot part way off so that you are neither propelling the car or regenerating the battery when you glide, i.e.: no arrows to or from the battery. When you coast, you take your foot all the way off the gas pedal and your car will decelerate relatively quickly as it regenerates power for the battery.

    I messed around with pulse and glide for a couple months a while back. I could not improve on just driving it sensibly (which is quite different from the people who pass me at 90 mph just so they can burn more gas getting to the obviously red light quicker so they can burn more gas idling longer at the light). :cool:
     
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  4. MsTee

    MsTee Junior Member

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    Thanks, Jerry. That's what I was looking for.

    Thanks, Sam. It didn't answer the question but I appreciate your thoughts.
     
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  5. bisco

    bisco cookie crumbler

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    i have been pulse and gliding my wife's hycam here in florida. i can pick up 2-4 mpg depending on trip length and traffic. right now, we're at 45 mpg on the meter, about 400 miles into the tank.
     
  6. Tideland Prius

    Tideland Prius Moderator of the North
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    Jerry's got it.

    The difference is whether you recharging or not.

    Glide is essentially like shifting into neutral (it's freewheeling). This allows the car to roll down the road with minimal friction (just air resistance, friction from the tyres and friction from the internal components). This methods allows you to travel the greatest distance before the next pulse.


    If you coast, that means your foot is completely off the accelerator. When that happens, the car is ever-so-slightly slowing down as the car is using the electric motor (MG2 in this case) to slow the car down by creating resistance (this also charges the battery, which is why you see arrows going from the wheels to the motors to the battery). This means the distance you're travelling with the engine off isn't as long as it could've been because you were being slowed down by the electric motor.


    Lifting off completely to shut down the engine then lightly reapplying the accelerator will get you into glide mode. Press to hard and you're in EV mode (battery --> motor --> wheel). However, don't freak out if you can't find the exact balance. If you're lightly in EV mode, that's fine. Unfortunately, Toyota doesn't tell you how much power is flowing (e.g. by changing the size of the arrows or any other indication) so don't concentrate too hard on finding that arrow-free moment. As long as you're lightly EV-ing, that's just as good :).
     
  7. ETC(SS)

    ETC(SS) The OTHER One Percenter.....

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    Asked and answered.

    Sam is right though.....
    It's easier to just hypermile like you would with a regular car.

    See also: Law of diminishing returns
     
  8. MsTee

    MsTee Junior Member

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    Thanks, Tideland. I've been watching the videos on the subject and, thanks to replies here, I think I've now picked up all the nuances.

    Just drive it is probably good advice for everyone, however I want more. I want to play with the car and enjoy all the small pleasures as well as the big ones :)
     
  9. Gasoholic

    Gasoholic Junior Member

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    The only thing about hyper-mileage driving, is pay attention to the road, not the gauge! Watching the ECO meter all the time is distracting and could cause an accident. If you use it for a while you can learn how the car reacts to throttle pressure and not look at it so much.
    Have you seen the commercial for the insurance company, the guy's head sticking out where the GPS display would be, Mr. Chaos? Not really funny, but very true, she can't stop playing with his face (the display).
    Gasoholic
     
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  10. MsTee

    MsTee Junior Member

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    Good advice.
     
    #10 MsTee, Mar 5, 2017
    Last edited: Mar 5, 2017
  11. edspecR

    edspecR Member

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    hate to nit pick, but i don't see why gliding is like shifting into neutral. this isn't the first time i've heard this comment, but i feel like it implies that shifting into neutral in a normal non-hybrid would be more efficient than leaving it in drive--which it technically isn't. I mean we're not arguing by much, but ceteris paribus, coasting in neutral in a non-hybrid post-90s car uses more gas than leaving it in drive. Gliding, from how i understand it, is driving in a manner that doesn't charge or recharge the battery. Efficient, but definitely not neutral.
     
  12. bisco

    bisco cookie crumbler

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    it is neutral for a prius. gassers are different, but prius neutral is just easier. you don't have to watch the hsi or try to feather the pedal, which is almost impossible.
    that being said, the unknown quantity is the most efficient rpm's for pulsing.
     
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  13. jerrymildred

    jerrymildred Senior Member

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    It's as neutral as you can get anyway. ;)
     
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  14. bisco

    bisco cookie crumbler

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    exactly.
     
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  15. edspecR

    edspecR Member

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    ah ok, so when likening gliding to neutral, we're talking hybrid neutral, not ICE-car neutral. got it :)
     
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  16. bisco

    bisco cookie crumbler

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    right. trying to adjust the gas pedal and paying attention to traffic is difficult, and possibly dangerous. you're always regaining a bit (bad) or powering a bit (not so bad). in neutral, it's done, but may be illegal. (really bad)
     
  17. Sam Spade

    Sam Spade Senior Member

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    So here's the thing for me:
    These vehicles are designed to RECOVER some energy when slowing down or stopping.

    For this "glide" thing to work for a net gain, you would almost have to be psychic so that you would KNOW EVERY TIME if you really were going to have to slow down a significant amount or not.

    So that leaves conditions when you are "cruising". During the glide phase, you slow down which you must recover from by expending energy.
    The whole thing seems like the driver is expending more of HIS energy that what he might save with the engine.

    OCD at it's worst, IMHO.
     
  18. kevinwhite

    kevinwhite Active Member

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    In a conventional vehicle changing into neutral prevents fuel-cutoff so it's a trade-off between the extra friction of the car's inertia being used to rotate the engine or the fuel used by the engine while in neutral to keep it running. If you have a car with automatic stop-start it may be better to put it in neutral.

    With the Prius you need to change into neutral AFTER the engine shuts-off then you can get gliding without having to finely balance the throttle.

    kevin
     
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  19. fuzzy1

    fuzzy1 Senior Member

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    In a normal non-hybrid, it depends on the circumstances. I'll restrict this answer to manual transmissions, not automatics, i.e. no D gear. Except for the Prius, my household fleet has been strictly manuals for more than three decades.

    N-ICE-OFF (neutral, ICE shut off) is much more efficient than coasting in gear. No fuel use, no engine drag. It is used only by the hardest core hypermilers.

    For the easier and more common N-ICE-ON (ICE operating), it depends. The driver is trading off the fuel needed to spin the ICE at idle speed, versus the energy loss of engine drag needed to spin it in fuel cutoff mode. With traditional gear ratios at highway speed, that spin RPM can be fairly high, thus costing more energy than actively burning fuel at much lower RPM.
     
  20. Tideland Prius

    Tideland Prius Moderator of the North
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    Yep. Sorry I wasn't clear in the post :).

    And that's why you always see traffic waves. People are too lazy to anticipate and would rather react.

    You can do whatever you want as no one's forcing you to do P&G. P&G is just a technique that you can apply to increase mpg. Nobody's gonna burst a vein if they didn't hit 25mph before they had to pulse again. Just go with the flow and adjust on-the-fly.

    Did that today and I was surprised that a delivery van (those ppl always seem to be in a hurry to get stuff delivered on time) followed me. Not before he was changing lanes to see which was faster but eventually he just settled being behind me cause he figured out, I'll get to the light as it turns green, and end up being the faster lane. I'm sure he wasn't doing it for FE. I was and ended up with 61.8mpg for that trip in a 7.5 year old Gen 3.
     
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