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Gliding in Neutral

Discussion in 'Gen 2 Prius Fuel Economy' started by andyprius, Nov 8, 2005.

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  1. andyprius

    andyprius Senior Member

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    Perhaps this question was answered before, I can't find it. When driving primarily in Neutral ( thru continuous acceleration and then deliberately shifting into Neutral and gliding about 50 to 80% of stretch) The AMPG readout does not reflect an increased MPG. It shows either the same or slightly less....Why is that? Driving conditions: Suburban.
     
    #1 andyprius, Nov 8, 2005
  2. hdrygas

    hdrygas New Member

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    Well you opened Pandor’s box (again!). I would do a search on the topic. My take you can do the same thing by feathering the accelerator. It takes a bit of learning especially if your feet are numb like mine but it can be learned. If I can do it you can.
     
    #2 hdrygas, Nov 8, 2005
  3. maggieddd

    maggieddd Senior Member

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    that's not what he asked is it?
     
    #3 maggieddd, Nov 8, 2005
  4. DaveinOlyWA

    DaveinOlyWA 3rd Time was Solariffic!!

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    well i cant imagine why your mileage would go down since when coasting in neutral, you are not burning gas (unless you have a lot of accessories running and need to recharge the traction battery) and you are moving. lots of people coast when they can and get spectacular results.
     
    #4 DaveinOlyWA, Nov 8, 2005
  5. andyprius

    andyprius Senior Member

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    Right now Im thankful for any reply. Yes I am aware of the feathering and have done it many times, however it is not positive and the battery must have a modicum SOC. With forced (deliberate ) neutral, the car has fantastic free wheeling. This time Im going to drive the whole gas tank in this manner and then calculate my mileage. ( I always chickened out before because the AMG did not concur with my method ) I think one of the Advisors mentioned: that no gasoline usage = NO MPG info. DAN, was that you??? I'm not sure this makes sense as some gas is used to get the car to a slight overspeed condition......to glide
     
    #5 andyprius, Nov 8, 2005
  6. andyprius

    andyprius Senior Member

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    Negative on all counts, engine never runs while gliding and my question was ....."Why is this apparent improved mileage not showing up on a continous basis as an improved Average MPG Reading"
     
    #6 andyprius, Nov 8, 2005
  7. andyprius

    andyprius Senior Member

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    Where are our experts now????
     
    #7 andyprius, Nov 8, 2005
  8. efusco

    efusco Moderator Emeritus
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    What is AMPG? Average MPG--you mean the one on the consumption screen?

    If so, then simply using Neutral is not any kind of guarantee of improved gas mileage, it must be use properly. More importantly is how you accelerate, slow down, use momentum and regenerative braking, etc. The, of course, all the usual factors come into play like weather, tire pressure, etc.

    I can pulse and glide my way to lower gas mileage easily. The key is taking advantage of situations to accelerate when it's most effective and gliding when it's most advantageous.

    If you read the marathon thread where they went 1400 miles on a tank there's quite a lot of the how-tos of pulse and glide.

    Also, remember that when you're in neutral you get no regenerative braking. Further, just b/c you're in neutral doesn't, AFAIK, mean that the ICE can't still be running...though I doubt it would consume much fuel.

    So, what's you driving experience, how many miles, average mpg, what techniques have you tried up to now, etc. What speeds are you using this neutral glide in and what traffic/road conditions?
     
    #8 efusco, Nov 8, 2005
  9. hdrygas

    hdrygas New Member

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    You need and independent monitor of the system. ScanGage or other will show you that the MFD is correct when you are gliding, if the engine is at temp. The MFD is not a good gage of when the ICE is running.
     
    #9 hdrygas, Nov 8, 2005
  10. andyprius

    andyprius Senior Member

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    Thankyou for your reply Dr. I'll try to cover each point. Yes, consumption screen, acceleration is medium to about 5-10 over speed limit, traffic is suburban, basically from light to light, or to stop sign. Timing of lights and traffic when possible. weather in Sacto, warm still, Tire pressures kept at 44Lbs all around (Bead pressure) Also regenerative breaking is accomplished with each slowingdown for either stop sign or traffick light. SOC normally kept in the blue ( or purple) Car has about 20K miles on it now, trip across country produced 54MPG at about 60MPH with CC. That all said I expected either very much improved MPG on the consumption screen or, very much worse! Instead the computer seems to be unaware of my efforts, why is that? TY
     
    #10 andyprius, Nov 8, 2005
  11. igotthewantsforprius

    igotthewantsforprius New Member

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    what is the ICE
     
    #11 igotthewantsforprius, Nov 8, 2005
  12. andyprius

    andyprius Senior Member

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    Interesting, I thought the only way to know if the engine was operating,running,powering the car WAS to look at the MFD.
     
    #12 andyprius, Nov 8, 2005
  13. andyprius

    andyprius Senior Member

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    Internal Combustion Engine
     
    #13 andyprius, Nov 8, 2005
  14. aka007ii

    aka007ii New Member

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    Internal Combustion Engine
     
    #14 aka007ii, Nov 8, 2005
  15. aka007ii

    aka007ii New Member

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    2 minutes before me. :p
     
    #15 aka007ii, Nov 8, 2005
  16. andyprius

    andyprius Senior Member

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    IF........ the MFD cannot be believed in this circunstance, what else is false or misleading on the MFD also, the AvMPG vertical bars do not show past the initial 5 minute point. I also expected them to be maxed out. I think in neutral the Computer is totally out of the picture.
     
    #16 andyprius, Nov 8, 2005
  17. hdrygas

    hdrygas New Member

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    OK the MFD does not always reflect the actual performance of the ICE. The ScanGage can be found here http://www.scangauge.com/. It is very basic and supplies generic data on the car. If you are a geek with bucks you could go this route and get more information; http://www.vassfamily.net/ToyotaPrius/CAN/cindex.html, if you are lucky and do not have the Nav system you could try this, the CAN View; http://priuschat.com/CAN-VIEW-Recovered-t11644.html. Those are the choices for today. Tomorrow is another story.
     
    #17 hdrygas, Nov 9, 2005
  18. andyprius

    andyprius Senior Member

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    Thanks for the information, now I have to digest it. Andy
     
    #18 andyprius, Nov 9, 2005
  19. efusco

    efusco Moderator Emeritus
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    Again, I'm not sure why you expected to see such a change. If you're already driving near maximum efficiency and your use of neutral/glide isn't ideal it's likely to be a 'wash' as far as overall MPG goes. In other words, if you're sometimes using it at times where overall mpg would be improved, but you're also using it sometimes where it's having a negative impact on mpg, then they'll balance out. Any time you start using 'creative' approaches to driving (pulse/glide, neutral, EV mode, etc) you have to realize that you there are times where it can help, but times where it can hurt and it takes time and practice to realize those times and take advantage of them.

    My only other concern is your mention of no bars on the consumption screen after the first 5 minutes...That seems odd. Frankly I haven't bothered with driving in neutral enough to have noted that affect, if it's universal. But it doesn't seem right, I'd think you'd still see bars on the graph even with frequent use of neutral.
     
    #19 efusco, Nov 9, 2005
  20. littleprius

    littleprius New Member

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    Does gliding in neutral at all damage the ICE, electric motor, or batteries?
     
    #20 littleprius, Nov 9, 2005
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