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I've been experimenting with the HCH II and the I2 and I'm trying to determine if, on the longer down slopes of the rolling hills I encounter at a few points on my daily commute, placing the CVT in neutral, which does not cut fuel flow to the engine and cuts regen, will still improve FE. It appears to raise FE as the cars maintain speed well on the down slope and the iFCD can raise by several .10 of a mpg. However, the benefit of regen and fuel cutoff is lost. Which is most efficient? neutral ICE-on rolling downhill, or CVT engaged charging the IMA pack? Or does it depend on where the SoC is?

So far I've been averaging mid-50s with the Civic and the Insight to work, and dropping coming home by 3-6 mpgs. More of the downhill runs are on the return trip so I'm curious to see if I can narrow the difference.

Mike

The lost regen opportunity would bother me, ie: if you do some behaviour that reduces regen, long and often enough, you might be reducing your battery's life span. You're using assist getting up the hills, and the car's designers anticipated recouping that spent charge going down the far side.

I would say it depends on your SoC. In general, unless you're coming to a stop or slowing down to a curve (i.e., you need to be slowing down anyway), you're better off coasting in neutral than taking advantage of DFCO in gear.

For a hybrid, the caveat is that you should only do this if you can maintain a decent SoC. The last thing you want is a forced regen on a climb, pushing your engine out of optimal BFSC and making it less efficient. You should coast in neutral only if the upcoming climb is small enough that you can get up it without incurring a regen midway. Depending on the climb, it may be that the optimal solution is to coast part of the downhill in gear and part of it in neutral. You want to reach the top JUST SHORT of regen kicking in. Of course, on the next downhill after that, you WILL need to put it in gear to restore your SoC. It all depends on the terrain.

Certainly if the descent is big enough to fully top off the pack then you might as well throw it in N once it's full.

If optimal fuel economy and efficiency is the goal then operating the vehicle in N is definitely not the best option.

In fact, we often discourage folks from doing so because it defeats one of the most critical features these hybrids are designed with and that is the ability to soft-glide with minimal drag and no fuel use.
To glide all we do is watch the instruments and let our right foot do the work... and the more often you do it the better you get at it.

In longer descents using a few regen clicks (will help save your brake pads) and will help preserve the SoC better in the next climb and even allow you to do a bit of EV on the shorter segments and light descents without using any fuel.


Cheers;

MSantos

In my experiance it does give better mileage. I believe it is because you are taking out the engine friction that would normally be a slight drag and shorten your coast distance. I do it at times and it really seems to help. Do be aware of the SoC. If you are getting low, then I would work the car normally and not coast in "N".

I would believe the iFCD. It's numbers would also include any fuel cutoff. you do loose the regen, but I shift into "D" again at the end of the coast before a stop and get regen that way, or use other normal stops and slow accels to balance things.

I have found the gas pedal is your best friend in the HCHII. Only touch the worthless CVT input device for P,D,R. It would seem the whole bloody car was designed around the foot input device.

It has no coasting magic. CVT see's to that. And believe it or not the current gen Civic is not a good coaster even with a MT. You want to coast look at what a 7th and yes even the 8th gen Accords can do.

If you don't have at least one of the last three update's on the car get one. The newer updates seem to control the pack much better. The one that came on our car was ok by me over all.

It's all in the throttle. I can go hardcore in the HCHII and bring the mpg up to really impressive levels. But it's not worth the work. The gas pedal alone give's me great results. :)

My MZ3 will out coast the HCHII.