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 Post subject: Re: Coasting
PostPosted: Tue Nov 11, 2008 10:27 pm 
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richard schumacher wrote:
efusco wrote:
I don't recommend the practice to anyone who's not an experienced driver on familiar roads that can give the necessary attention to the speed, ICE condition (on or off), and do this in a safe manner.

That's the problem, inn't. People like to flatter themselves by thinking that they can pay attention to multiple things, but the more attention that is required for a task the greater the chances for error. Better to leave it in "D" and devote more of one's attention to outside conditions and events.

I disagree, everything is degrees and relevance.
One could argue that it is safer to have the radio off. And never talk to passengers...and even safe to have no passengers. And safer yet to drive under the posted speed limit...and safer yet to never drive at all.

You suggest I delude myself, I suggest I'm one of the safest drivers on the road in large part b/c of the high degree of attention I pay to my driving technique, road and traffic conditions as a means to the end of higher fuel economy.

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 Post subject: Re: Coasting
PostPosted: Wed Nov 12, 2008 7:37 am 
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I agree with Evan's points. Issues of the legality (in many states) of downhill neutral and theoretical over-revving of MG1 are real. But let's assume level terrain, which puts those aside. Neutral gliding is at least as effective as pedal-control gliding as a fuel-saving technique, and possibly better. As Evan indicates, there is higher current flow out of the battery with the latter, which must be replenished with ICE power. It actually seems to be a very low-power EV mode. See this for more:

http://priuschat.com/forums/prius-techn ... utral.html

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 Post subject: Re: Coasting
PostPosted: Wed Nov 12, 2008 6:18 pm 
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Peace, Evan, peace. I'm certain that you are a very safe driver. I was writing about myself and other average members of the great unwashed masses of humanity. Picture one of us, if you will, cruising through the Great Smokey Mountains, one hand on the wheel, one hand hovering over the shift lever, one eye on the road, one eye on the Canview, one side of the brain humming along with the iPod, the other enjoying the beautiful autumn foliage, and then AHHH! A deer! A rockfall! AHHH!

Not a pretty picture, is it :_> Ordinary people need to keep all of their hands on the wheel and all of their eyes and attention on the road, as much as possible.

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Last edited by richard schumacher on Thu Dec 18, 2008 10:12 am, edited 1 time in total.

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 Post subject: Re: Coasting
PostPosted: Fri Nov 14, 2008 3:28 pm 
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I have repeatedly warned against this practice, for reasons of legality and control. I agree it is only marginally less controllable than leaving the car in "D".

The reason there are laws governing it is because, "in the beginning" vehicles had only a vague approximation of brakes. The engine could actually provide more braking power than the "brakes". So leaving the vehicle in gear was considered mandatory! The brakes were mostly for parking. ;)

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 Post subject: Re: Coasting
PostPosted: Tue Dec 16, 2008 10:36 pm 
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WOW. I never thought this post would generate this much interest.

Guess I wasn't the only one trying this method to "tweek" my gas mileage.

I have a 3 mile stretch of downhill that is open and not very dangerous. I drive it daily and found that if I put it in Neutral I was able to coast and end up with a greater speed going downhill then if i left it in neutral. I also am able to coast another 1/2 mile before I shift back into Drive. So, I go 3 1/2 miles ....for free....I think, unless I am ruining some parts that I know nothing about. So, that is how this all started.

Thanks for the feedback.

Hal


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 Post subject: Re: Coasting
PostPosted: Tue Feb 17, 2009 12:02 pm 
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Location: San Mateo, CA
In CA its illegal to coast in Neutral besides why would you want to? There is a long hill I go down and I lightly press the breaks while going down to charge up the SOC. I used to use the B position but found out that could use more gas so I don't do that any more. When I get to my turn off I hit the EV button and drive the last mile and a half in EV mode and the indicator is still green when I get parked.

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 Post subject: Re: Coasting
PostPosted: Tue Feb 17, 2009 12:23 pm 
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It's illegal to speed. It's illegal to slide thru a stop sign. It's illegal to not pay taxes on internet purchases. And on....and on...and on!!!

How long do you think your brakes will last if you ride them down hill?

What is an "EV button" I don't have one on my 2006 Prius, or at least I don't know were it is!


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 Post subject: Re: Coasting
PostPosted: Tue Feb 17, 2009 1:23 pm 
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EV button. Installed on Japanese and European models. Under some conditions keeps the ICE from starting and allowing you to "play" in parking lot's under electric power. Can be purchased from a private source but could cancel the factory warranty on an American car if installed.
Toyota says to drive the Prius as a normal car. The brakes will last a hundred thousand miles if you ride them down every hill you encounter for the next five years.


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 Post subject: Re: Coasting
PostPosted: Tue Feb 17, 2009 2:06 pm 
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So....normal for Japanese and European models is not normal for American cars!!!! I know, it has something to do with the warranty on the batteries.

If you install an "EV" button on an American Prius is it illegal, it must at least be against the law of warranties!!! , as it voids the warranty? Is that "illegal" more or less then the "illegal" of coasting? 8)


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 Post subject: Re: Coasting
PostPosted: Tue Feb 17, 2009 3:12 pm 
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It's not illegal for you to void the warranty, just silly :_> It *is* illegal in many places to coast in neutral, but as a practical matter it's hard to see how a cop could notice that a Prius was coasting in neutral.

If you anticipate needing the brakes on a downhill then use D to absorb that energy instead of wasting it. If D isn't enough to keep the speed reasonable then use B.

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 Post subject: Re: Coasting
PostPosted: Fri Feb 27, 2009 6:48 pm 
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OK I give. Why not recharge the battery while coasting downhill? Its free energy and provides a "natural" drag to keep your acceleration rate down. And while in drive I can glide where I need to and/or control the amount of regeneration with the gas pedal. As an engineer I find it appalling not to take advantage of not only kinetic energy given to you but a build up of motive energy.

As an engineer I must say you might save a couple of hours of motor life by not using your motors but that is dwarfed by the hundreds of times the motors are utilized on every trip. And yes I tried the old putting in neutral once and when my battery actually went from green to blue while going downhill, I never did that again. Heck I drive my wife nuts because I practice energy driving. I keep my gas pedal pressed in one position while thruway driving and take advantage of every little hill. I use my cruise control when I'm tired.

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 Post subject: Re: Coasting
PostPosted: Sat Feb 28, 2009 12:43 am 
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halsport wrote:
How long do you think your brakes will last if you ride them down hill?


Almost forever. Light to moderate brake pedal application does not apply the rakes, it just makes the motor operate as a generator and recharges the battery. The brakes only operate when you press the pedal hard, brake with the battery already full, or during the last 5mph or so of stopping. I have many hills on my commute, and after 90,000 miles I have at least 80% of my pad life left.

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 Post subject: Re: Coasting
PostPosted: Wed Mar 18, 2009 10:06 pm 
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from what i gather, there is no reason in the world to put the trans in N. just use the previously stated "glide" method. it is essentially the same as neutral, since none of the motors are running nor is it regenerating. i've noticed that when "gliding" the car coasts much faster than in D. this should be a no brainer...


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