hypermiling by coasting in neutral

Discussion in 'Gen 2 Prius Fuel Economy' started by ChrisPR77, Jan 9, 2017.

  1. ChrisPR77

    ChrisPR77 Junior Member

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    I have learned coasting in neutral is actually illegal. I had been practicing some hypermile technique on my 2000 honda civic std I had leaned on youtube before buying my Prius. This involved coasting in neutral and shutting the engine off at times. I found out that caused me to loose brakes after 3 pumps but steering remained unaffected. So it seemed turning the engine off while coasting was a little too excessive. I already had a standard transmission so the neutral coast felt natural. I didn't even know what I was fooling with was illegal at the time. I was getting max epa highway out of the civic 33mpg for about half city and half hwy. A pretty good number.

    I bought the Prius a few days ago and I started fooling around with it in neutral when I found out it has towing restrictions and that I am not supposed to be coasting in neutral with it. There are a number of people in various posts claiming they have done it for years in the Prius and how they will continue here on Pchat.

    My question is if it will tear up the car why does the Prius allow you to shift from D to N at speed? The car is smart enough to keep you from shifting into R. I think the coast would be a good tool to get better mpg if a person knows the risk involved. The Prius does it so amazingly well, way better than the Civic. I could see getting ridiculously long neutral coast in the Prius. It almost felt like the car was designed for it. Mixed with regular driving you can keep the battery plenty full so don't use that as an excuse.
     
  2. JimboPalmer

    JimboPalmer Tsar of all the Rushers

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    N will cause no damage to your Prius.

    It will only hurt your gas mileage and drain your battery, which cannot charge in N.

    Toyota is required by law to have N, you are not required to use it.

    One idea for N, once a month, stop in N, to clean rust off your brakes.
     
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  3. digbywombles

    digbywombles Junior Member

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    You can get the effect you're after by keeping it in "D", and lightly touching the accelerator pedal - just enough to take the power bar out of the "charge" area.
     
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  4. jerrymildred

    jerrymildred Senior Member

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    Driving in neutral is illegal in every state where I've lived. And, as Jimbo said, it will run down your traction battery if you do it enough because the Prius doesn't charge in neutral. In fact, my Gen 2s had a warning that popped up on the MFD screen when I inadvertently put them in neutral.

    Digby is right. You can feather the throttle while keeping an eye on the energy monitor on the mfd and make all the arrows disappear. That means the battery isn't powering the vehicle, the engine is off, and no energy is being put back into the battery. Let off the accelerator, and you'll be regenerating again. It's a skill that doesn't take long to acquire. No need to take it out of drive to coast. It's an amazing vehicle.
     
    #4 jerrymildred, Jan 9, 2017
    Last edited: Jan 9, 2017
  5. valde3

    valde3 Senior Member

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    How can driving in neutral be illegal? With manual transmission? When you do shift between gears there’s always neutral in between. Is there a time limit on how long you can stay in neutral (how fast you have to change the gears)?

    And why is it illegal to begging with?
     
  6. ChrisPR77

    ChrisPR77 Junior Member

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    It's a neutral coast in the civic after I learned about it I could do a mile long coast at 70 mph anticipating my exit with a hill. There are some really insane recorded neutral coast over multiple miles. I imagine at one point it was addressed because of wrecks. I could imagine people getting to very high speeds using the technique on large hills. The vehicle is also less stable with the engine not engaged.
     
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  7. ChrisPR77

    ChrisPR77 Junior Member

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    Okay. So was it possible I hurt my new car in the first couple of days I had it?
    1) the manual doesn't say what to do if your car spontaneously pops into neutral, it just says don't do it. (this happens by a number of things including hitting the park button while driving), so what should we do if it spontaneously pops in neutral?
    2) manual states damage to any towing other than front wheels lifted or flat bed.
     
  8. ChrisPR77

    ChrisPR77 Junior Member

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    Interesting, in the manual it states towing restrictions to front wheels lifted or flat bed. Supposedly some tow trucks ruined some cars?
     
  9. Mendel Leisk

    Mendel Leisk 'Orrible Oracle

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    More likely just losing the "power-assist", brakes are still there, just a little heavy feeling?

    Yeah with Prius I would just do this, more convenient/simpler/safer.
     
  10. jerrymildred

    jerrymildred Senior Member

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    I'm sure you didn't hurt it. It just prevents the battery from being charged something like leaving it sitting w/o the engine running, but not shut off -- the difference being, if it's sitting motionless in park, the engine will start and charge the HV battery if needed. In neutral, the engine won't charge the battery and it will eventually go totally dead and that can get expensive. As an experiment, try starting it up and then set the parking brake and put it in neutral to see if you get a warning message. Now that I think of it, I should try that on my plug in. I'll bet I get the same message or similar.

    As for towing it with the front wheels on the ground, that will almost for sure break something. When you shut it off, it puts itself in park, so it will either try to turn the engine or break something in the drive train. If traction is the weak link, you'll just rub the bottoms off the tires, I suppose. Probably leave a LONG skid mark. LOL!
     
  11. valde3

    valde3 Senior Member

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    Doesn’t really make sense as you can get a car going even faster by just leaving it in gear and using the throttle pedal. There really isn’t a difference in vehicle stability unless you’re talking about sliding a car on gravel surface and using throttle to control the sliding (which most of people can’t do).

    There are two ways to damage the Prius by putting it in neutral while driving:
    -Draining the hybrid battery bellow 2 bars. This is really hard as you normally have 4…6 bars while on highway. You would need impossible long coast. But this can happen while stationary so don’t use neutral.
    -Driving less than 42MPH with engine not spinning then shifting to neutral and accelerating (on downhill). This will slowly wear the hybrid transaxle. So doing this once or twice is not that bad but you shouldn’t do this.

    Prius is always powered on some mode wearing down battery or OFF in PARK. So to manual just tells you to tow it in OFF and PARK with at least front wheels of the ground.
     
  12. Moving Right Along

    Moving Right Along Active Member

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    To the best of my knowledge, when towing a car, the drive wheels (front wheels on FWD, rear wheels on RWD) are always the ones to be lifted in order to prevent transmission damage. I'm not sure what the procedure is for 4 wheel drive vehicles.
     
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  13. Sam Spade

    Sam Spade Senior Member

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    NO.
    Don't worry, be happy.
    Just stop doing it.
    The car will shut the engine off whenever that is the economical thing to do.
    Coast without releasing the gas pedal all the way.

    Forget about "hypermilling". It is dangerous and pointless in a hybrid.
     
  14. Mendel Leisk

    Mendel Leisk 'Orrible Oracle

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    Maybe your definition of hypermiling is different. I think it encompasses all sorts of safe practices to economize.
     
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  15. ETC(SS)

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

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    I think they're about to take the horse off of life support - but "hypermiling" with a Prius in neutral......isn't.

    Good Luck!
     
  16. JimboPalmer

    JimboPalmer Tsar of all the Rushers

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    Valde, Chris is in California, where it is only illegal if it is downhill. In theory it is legal going uphill.

    Vehicle Code - VEH
    DIVISION 11. RULES OF THE ROAD [21000 - 23336]
    ( Division 11 enacted by Stats. 1959, Ch. 3. )
    CHAPTER 3. Driving, Overtaking, and Passing [21650 - 21759]
    ( Chapter 3 enacted by Stats. 1959, Ch. 3. )
    ARTICLE 2. Additional Driving Rules [21700 - 21721]
    ( Article 2 enacted by Stats. 1959, Ch. 3. )

    21710.
    The driver of a motor vehicle when traveling on down grade upon any highway shall not coast with the gears of such vehicle in neutral.

    I have no idea what the law is in Finland, sorry.

    It is still a bad idea in Finland, but I can't confirm it is illegal.

    Mississippi law is slightly tighter, as for trucks it also prohibits putting the clutch in. (This matches the Washington State law i learned in Driver's Ed)

    2013 Mississippi Code
    Title 63 - MOTOR VEHICLES AND TRAFFIC REGULATIONS
    Chapter 3 - TRAFFIC REGULATIONS AND RULES OF THE ROAD
    Article 25 - RECKLESS OR CARELESS DRIVING AND MISCELLANEOUS RULES
    § 63-3-1207 - Coasting upon down grade


    Universal Citation: MS Code § 63-3-1207 (2013)

    The driver of any motor vehicle when traveling upon a down grade shall not coast with the gears of such vehicle in neutral.


    The driver of a commercial motor vehicle when traveling upon a down grade shall not coast with the clutch disengaged.
     
  17. CooCooCaChoo

    CooCooCaChoo Active Member

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    The only time I've ever had to put it into neutral and coast is when going to the central California coast. When going down the mountains, you will hit full battery before you come off the mountain. Overcharging the battery is obviously very bad. When this happens, you have to do everything to drain the battery: headlights, radio and AC. Usually this still isn't enough.

    Sometimes the only option to prevent the battery from overcharging and exploding is coasting in neutral.
     
  18. Kevin_Denver

    Kevin_Denver Active Member

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    There is a single circumstance (that I know of) where you can improve fuel economy by using neutral instead of drive: To coast below 7mph. The Prius disengages regenerative braking at about 7mph (I've felt it do this between 5-10mph). Below 7mph, it sends a small amount of power to the electric motors to cause the car to creep similar to an automatic transmission vehicle. On the commute to one of my clients, there is a downhill on-ramp with a light to let cars go two at a time. Traffic creeps down the hill at 3-4mph until cars reach the light. Therefore, to keep from using electric energy going down the hill, I put the car in neutral and glide slowly down the hill until I reach the light and switch to D and drive off. Probably makes about 0.1% difference in my commute, but every little bit helps (or at least this is what I tell myself haha)!
     
  19. JimboPalmer

    JimboPalmer Tsar of all the Rushers

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    You can't get to N without the car being in READY, so the tow truck is not towing a Prius in N very often.
     
  20. JimboPalmer

    JimboPalmer Tsar of all the Rushers

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    The correct option is the B gear from the summit. The Prius will never overcharge the battery, it will quit doing any regen and rely on engine and friction brakes.
     
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