I can hear the uproar already... but hear me out.

Put about 500 miles on the car since we got it last week. I've noticed that the IMA engages very little. If the ECO is engaged and you start up an incline instead of using the IMA, ECO shuts off. Also when accelerating from a stop or anytime really, it hardly engages. Only when you really romp on it does the IMA help out.

To me I think the IMA should be more active. Any start from a stop and any time an increased load is seen while in ECO IMA should engage.

However I don't think the Hybrid design is a total waste. The dealer told us that the 15 hp increase from the base Accord and the Hybrid is due to the IMA. While that sounds good in theroy I'm willing to bet it's more due to the lack of parasitic power loss to accessorys such as a traditional power steering system. I havn't had a chance to really inspect under the hood and the many plastic shrouds but I would venture to assume that the A/C and possably also the water pump is driven electrically as well. All three accessorys could very well eat up 15 hp. They also have a very real effect against MPG.

I mention these three accessorys because while the ICE is in auto-stop you would still want them to be "live". In winter you want heat so the water pump is nessicary and in the summer you want to be cooled down so A/C makes sense as well. Power steering is a given.

Also the auto-stop helps some in mpg but I would guess that it's not a huge boost to MPG.

So while I don't think that IMA is the future of Hybrids I do see it as a viable accessory. Just think if all autos had it? If every car had a 10% increase in MPG? And with that kind of production level's cost's could easily be kept to a resonable level. Hell it only cost an extra $3,000 over the base Accord EX price as it was. Certainly nothing that breaks the bank.

so are you all ready to lynch me?

 

You are pretty much on the mark for the Accord IMA, it's not really directly contributing much to MPG by assist, most of the gains are with the ECO mode and autostop, but that is facilitated by the IMA system. The 15hp difference would only be noticed if you request more power than the normal v6 would deliver, so you aren't really benefitting much since the engine isn't downsized like the Civic and Insight. Personally I think Honda aught to make a 4-cyl HAH that would take advantage of a downsized engine with a good electric assist to give it a v6-like feel with better than typical 4-cyl economy.

 

Agree with Schwa mostly here. 4cyl with 6cyl feel (a la FEH) would be wonderful.

Think of the IMA in the HAH as an electric supercharger. It will help in ECO mode, but its a tight margin and nontrivial to keep it there without calling up the other 3 cylinders. It takes a trained geather touch on the pedal that you will achieve over time and practice.

Many others also agree with you that a more liberal usage of IMA (and more eco mode at low speed) and/or a 4cyl version would be a superior combination for efficiency.

In Honda's "defense" they never claimed this to be super-efficient, just more powerful and a little more efficient. They specifically targeted this to those who want more power and some more efficiency. So everyone received fair warning. The HAH gives Honda best-in-class mpg which is one of Hona's primary targets in every segment they compete in.

But hey, its a start. Honda and all makers will expand the lineups and options. And the cylinder shutdown capability is worth it by itself. And we STILL get better combined EPA mpg than EVERY single 2005 big-3 vehicle. All while sitting in leather-wrapped luxury.

 

jenbrant, allow me to paraphrase your complaint:

After 500 miles, I only stomped on the gas pedal *once*. So what is the point of the extra HP ??

Indeed.

 

Don't put the IMA in the Smithsonian just yet. It's simpler than the HSD and should be more reliable than the HSD over years of driving. A car without an IMA is still drivable.

Honda designed the IMA to augment an already efficient gas engine. It will probably assist a fuel cell vehicle next.

As regenerative braking and battery technoligy improves, the IMA will get better and better.

 

As an HSD driver I would add: what ultimately matters is how well a system performs in actual use.
Take one look at the GH mileage database, and you will see that IMA in the HCH performs as well as HSD in the Prius II.
I would hardly call that a joke. It works!

 

I agree, I wish there was a "button" that could engage the IMA at will. Also, an override button to cancel charging at the wrong moment, like up a hill.

 

I don't know if its realy true that IMA vehicles will drive without IMA. Part of IMA is that it acts like an alternator. So when IMA goes chances are it will be like driving without an alternator. I'm not sure if the engine block has any place to mount an aftermarket alternator to replace the charging supplied by IMA to the 12V battery.

 

It certainly does, but we're talking in the context of the HAH. IMA plays far less of a role in the HAH- it truly is similar to an electric supercharger, providing boost when the already substantial assets of the V6 are tapped.

I get 41mpg in my HAH on my commute. I maintain 3-4 bars SoC, and see IMA assist maybe 2x, for a few seconds each- and that's if I screwed up and touched the gas too hard after one of my few lights.

The HAH's highway performance is overwhelmingly from VCM, not IMA.

Even in town, the only way I see IMA normally is if I am moving in a hurry. In this case, yes- the HAH will get better mpg than the equivalent 6-cyl. But if you drive gently in town as a rule, it will do just a little better than the equivalent small 6-cyl: mid-high 20s/very low 30s. Autostop is what generates most of the mpg improvements there, in my experience. And autostop requires IMA to be able to restart so fast, so in the end, IMA does help here too.

My analysis:
IMA is not a joke, but the HAH as implemented is not the ideal place for it as currently inplemented. The HCH or a 4cyl HAH is. But its a start, and the HAH is still an outstanding piece of machinery. It can only get better.

 

That's very true, and I would agree that the 6cyl HAH may not be the best implementation or showcase for IMA. The same could be said for the HSD though, with the HH showing very little increase in FE over the non Hy-Hy. A colleague of mine's wife drives the 4cyl Highlander, and averages about 25 mpg, or about the same as the HH in teh GH database.

On a similar note, the most extreme hypermilers reported on GH are using driving techniques that largely bypass hybrid technology. Burst & glide driving while minimizing current flow to/from the battery essentially bypasses hybrid technology. Yet what allows that is the auto-off and restart of the HSD in case of the Prius. That's why I believe that extreme hypermiling might actually benefit from simply having an auto off/on feature, and none of the other hybrid technology, combined with a small ICE.

So, when is Honda going to come out with a 4cyl HAH that maximizes FE rather than performance?