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Old 02-22-2015, 01:31 PM   #1 (permalink)
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Default Using Neutral Gear Shift

Dear Insight Community!

Having only recently migrated from a normal car to the Insight (2nd gen), i have a question; there is a certain part of the road i travel to wok which goes downhill in one direction ever so slightly so that i know by heart the exact spot to shift to neutral gear with my old car (which was a non-automatic car!) and let it "roll" so i use less gasoline; this works exceptionally well on this part of the road as i can go for about 1.2 kilometres without ever touching the gas pedal.
My questions is now - would this work with an automatic car like the insight, too?
Now i know the Insight using hybrid technology can conserve a lot of energy when going downhill, but fact is it does not do that as much on this particular road as i would expect it.

So first (as i have never driven an automatic car before) - is it "ok" to shift to neutral gear while driving and then later shift back to "D" while driving 80 km/h or would this damage the vehicle?
And second question - does it make sense to do that with the insight?

Thank you very much for your help in advance!!

Best regards,

Chritian
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Old 02-22-2015, 02:29 PM   #2 (permalink)
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You can, but you'd need some gas to keep the engine running.
Keying off is not a good idea imho; power steering, braking, stability control etc. may all be compromised. And re-engagement from neutral may be tricky at higher speeds.

There is however a good alternative.
When you are engine braking the fuel will be cut off (DFCO). In addition, the Insight will start generating electricity to boost the charge level in the IMA battery (left dial in the green part).
If you now push the throttle ever so slightly you can reduce that regeneration without ending DFCO.
Usually you can even get it beyond zero and use electric power as in EV mode. You can prolong the glide quite some then.
You have more control than in neutral - even on speed.
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Old 02-22-2015, 02:43 PM   #3 (permalink)
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If you shift to neutral the engine idles. Then there is a delay when you shift back to drive for it to configure the pulleys for the speed you are going before it will engage.

Its better to just use light throttle to "coast" in situations like that.



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Old 02-22-2015, 05:11 PM   #4 (permalink)
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Hi again!

Thank you for your fast and thorough answers!
So am i to understand correctly that basically i could do it, i would not damage my vehicle, but in the case of the Insight, it just makes more sense to try to get it to drive mostly via electric power at such road parts?

Thanks,

Christian
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Old 02-22-2015, 07:12 PM   #5 (permalink)
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I would limit my coasting to 2-3 miles with engine off. The engine turns the pump that circulates the fluid in the cvt. This helps to lube and cool it.

I use to do this with engine off, however after a few cycles and miles the IMA battery gets too low on charge and the car enter a force recharge cycle. THis lasts 3 minutes and basically ruins what gains you make.

By using the throttle to limit engine and recharging use you avoid the other problems.



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Old 02-23-2015, 12:33 AM   #6 (permalink)
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I don't think the OP ever suggested keying off, just shifting to N. While that might make some marginal difference in a regular manual shift car, coasting downhill with ones foot off the gas in an Insight generates juice. I kinda doubt anyone could out skill the Insight computer. But we humans like to think we have control


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Old 02-23-2015, 02:48 AM   #7 (permalink)
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I did some testing when I just got my UltraGauge.

When I drive at around 35 mph or 58 km/h at a constant speed on a windless day I may see fuel consumption as low as 2.5 l/100 km, about 90 mpg.
Per time, this is 1.45 lph or 0.38 gph.
When idling in N (with a warm engine) I use about 0.7 l/h, that is half what I need to keep moving at 35 mph...
the revs are pretty much the same; 1100 RPM.

When you're idling in D at the lights you'll see the revs drop lower, because of the mild load on the CVT clutch.
If you switch to N the revs climb and the fuel consumption drops, freed of the extra load.
So I do switch to N quite a lot; namely, every time when the lights outlast AutoStop.
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Old 02-23-2015, 05:25 AM   #8 (permalink)
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The other thing is, with enough juice in the pack, you'll be surprised what the Insight will do on a slight downhill. I've seen it give the slightest bit of assist to result in a roughly 1 mile long fuel cutoff glide maintaining 70 mph. I wasn't aiming to glide, just maintain speed.
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Old 02-23-2015, 05:15 PM   #9 (permalink)
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Thats one of the keys to higher than normal mpg. Coasting off the ramp on my way home accounts for a 4 mpg gain in my commute. Do that several times and it really adds up. If you time it right with stops or lights on your trip you will see you can get better mpg stopping from a coast vs going at a constant speed. This is kind of the bases of pulse & glide.

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Originally Posted by Uriel View Post
The other thing is, with enough juice in the pack, you'll be surprised what the Insight will do on a slight downhill. I've seen it give the slightest bit of assist to result in a roughly 1 mile long fuel cutoff glide maintaining 70 mph. I wasn't aiming to glide, just maintain speed.


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Old 02-23-2015, 11:21 PM   #10 (permalink)
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You might be missing out on some regen going downhill. Don't think the coasting in Neutral will give you measurable MPG gains, unless the downhill is really long. Most modern engines don't burn much gas when rolling downhill with the engine on and no power being added through accelerator while in gear. If the car is out of gear, the engine has to use gas to maintain idle.

Steady state on flat or slight downhill will yield excellent MPG with this car.
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