How to drive your third-gen

[hobbit]

I've been working on a document about the "hybrid system indicator"
in the third-gen Prius, slightly ironic as I don't actually own
one but have just enough time in one to see a lot of parallels
in running-condition thresholds to my own '04 and how I read
its add-on instruments. It's been mostly going on over at
Priuschat but I figured if a few folks here hadn't seen it yet
and are interested in helping refine the info, I'd drop another
reference thread over here for y'all.
.
_H*

[xcel]

Hi Al:

___I would hold off a bit as the HSI is more of a bad mimic. There are differences between going up and down into the threshold and it also depends on speed. The Prius-III is a mess between 42 and 45 mph and the high FE capability of P&G at speeds below 35 mph is not as high as it is with the Prius-II.

___Good Luck

___Wayne

[xcel]

Hi Al:

___A few more details...






___Good Luck

___Wayne

[ksstathead]

Good stuff, Hobbit.

Appreciate the link.

[hobbit]

You can't really judge by the instantaneous that way, I don't
think. Again, getting a monitor on a fuel injector line and looking
at open times [even just with a scope if we can't get the right
bits for a scangauge] will tell the true story on where "loaded"
really begins. But from what I felt and saw for LOD I really
think it starts about where you've got the HSI in most of those
shots. You also can't try to do any of this under cruise-control;
it's all way too variable in terms of where throttle control
winds up.
.
_H*

[xcel]

Hi Al:

___This was the best I could do after 1,800 miles, not a short jaunt down a local Interstate. This was also not with CC but a DWL scenario after an 8% SG-II offset was in place.

___We have discussed WS entry and exit as well. An SG-II will show a steady RPM in the high 980 range IIRC but about half way up the EV side of the HSI and she moves into an injector on like WS for some reason?

___Coming down through 45 mph, to evoke ICE-Off, let off to regen and than move to N will force it. Drop below the threshold and she is bouncing back and forth between ICE-On and a WS like ICE-Off. Very strange.

___Around town, P&G and SHM work as expected but the FE capability on the top end and bottom end are not as high as the Prius-II. Napa Valley’s 90 + was really mid-80’s with a 20 mph avg. speed? The Prius-II would be up into the 100’s on that route. From Chicago to New York and back allowed 800 + miles on a single tank both ways but not at 70 + like the Prius-II. It was 65.9 (actual top off to top off) and I was working it albeit with a light headwind heading out and a stronger headwind coming back.

___I have pics all over the place of this stuff but need to bring them altogether...

___And that damn 6 mpg over report by the aFCD

___Good Luck

___Wayne

[msantos]

Hi Al;

I totally agree with Wayne on this one.

Contrary to what many folks at PC believe (Including Ken & others) the HSI is not a tool I would trust at all in part because at best all it shows is the "power/energy requested" and not the "actual power/energy being used".
With this said, I will only use it when I need to manage my SoC by keeping the EV amplitudes and regen's to a minimum. On this front it is a useful gauge for me. On all other fronts (including the so-called P&G execution), I find it of limited to no use.

Cheers

MSantos

[hobbit]

I agree that there are some fairly well-known hysteresis effects in
all variants of the Prius, which is in fact one reason P&G works
when the driver forces hopping across those inefficient states.
But it sounds like my whole effort is being dismissed as wrong.
I said straight out that the HSI is not linear and heavily
affected by SOC and probably some other factors; it's not just
a fixed "mimic" of driver demand or something like that.
.
As far as I'm concerned the mid-speed problem with the Prius has
been solved long since, and it's just a matter of finding out a
few new specifics for the 3rd-gen. Yes, various readings are
"all over the place" -- iFE, for example, is *very* twitchy at
the low end of "loaded", showing anywhere from 50 to 80 mpg in
my car too, but for discernible reasons -- RPM changes a bit,
injector time widens or shortens; I see all that going on too
and have learned to play it reasonably well in my own car. I
just got back from a long one today showing 61.5 mpg over 500
miles, all highway with some rain, and I wasn't coddling it --
in fact going 65+ MPH for a healthy chunk of that time [mostly on
the downs]. That's not a bad showing for what more people would
accept as real-life travel speeds, I think.
.
Rather than suggest "holding off" on something already for the
most part published, how about detailing which parts you [xcel]
consider inaccurate, and offer some input for fixing it and
providing a solid document for the masses? What is your number
one display to monitor in a Prius, and why, and where do you
try to keep it? What was your primary efficient-running indicator
for, say, the Chi-to-NY run? The iFE? Something on the scangauge?
How do YOU define "DWL" in a Prius, as the physical throttle is
completely divorced from the driver's foot?
.
I think as people come to understand that thresholds and targets
can change quite radically in a running Prius, they'll learn to
understand what the HSI is telling them better. Your very own
example of falling out of WS at different thresholds is well-known
and detailed at length in my existing WS document, and I don't
expect the 3rd-gen behavior to be particularly different. I'm
confident that the 42 - 45 mystery area will be solved before
long, too.
.
_H*

[xcel]

Hi Al:

___I have to get some sleep but there are more than a few problems. It is not about what your car can and cannot do as we have been through all of that before. SHM while DWL on the highway for 70 + mpg's in a Prius-II. Regarding WS, that doc does not match the Prius-III either. You have to drive one with an SG-II to see the strange ICE-On/ICE-Off behavior between 42 and 45 either going up or coming down let alone above 45 and the WS changes. The Prius-III is nothing like the Prius-II when it comes to WS. This is also not about efficient or inefficient areas but simply achieving what many PC’ers never seem to be able to do and that is punch the damn thing into the 100’s around town and 70 + on the highway.

___Some of those guys tend to fool themselves into believing they both understand and know how to achieve what we do here daily but it is our job to stop the mis-information before it gets started as it confuses the new and future Prius drivers. I do not want to spend the hundreds of hours to remove the non-sense that some of those guys coerce others into believing just like we had to do with the Prius-II! It is bad enough that a strong core group of PC's include numbskulls that are attempting to redefine what Hypermiling is after both Manuel and Mike Sefton tell them exactly what it is without question. Let alone how the Jetta TDI performs when none of them have even driven one yet still for some reason know more than those of us who have I simply do not want to go there and you are moving awfully fast with this...

___Regarding 65 + mph, your average speed was probably more around 55 or so.


I was in the car but most certainly not at the wheel when Danny of PC
set the cruise at 65 mph yet a few slowdowns to turn around turned it
into a 50 mph avg speed.


And my DWL around the 50 mph avg speed mark including five
off-ramps to find the same station I did the intial top off fill at.

___Both of these results occurred in almost freezing temps and at night on our way to and from Sacramento, CA back to the NAPA Valley area.

___The new Prius-III doesn't really allow the slow speed stuff to get in the way w/ the avg speed staring at you and here is a result of a 60 + mph run from Chicago to well into NY before stopping for the night. The avg. speed ticked down from 54 mph to 53 mph while driving around Harry Clark’s home looking for a parking place.

Chicago to NY





From NY to Chicago


From NY with a 10 + mph headwind most of the way home as shown with the flags at a rest area.


Achieved with average highway speeds of around 52 mph into that damned head wind... which includes a downtown
stop near Erie for ALS to take a slow speed suburban and higher speed highway test drive, a rest stop every hour
or so including three for breakfast, lunch and dinner.

___The Prius-III SHM numbers are posted as shown as are the speeds so that is not the issue we are talking about.

___What I want you to be very careful with is the rates of acceleration or efficiency areas via HSI. I usually run from the threshold bar up to underneath the ECO bar and that will give 91.1 mpg around town with lights, with traffic, with impediments and with a warm-up hit over a scant 4-miles as I did this just a few hours ago in my parents 2010 while going out to dinner with them. Subtract the std. 6 mpg over report and you may find that the higher rates of accel with the HSI closer to the PWR end "may" lead everyone in the exact wrong direction. We do not need any of that 1,700 RPM stuff that the PC'ers were all hung up on for years when we were using lower R's and achieving far better results. This is the reason I said be very very careful when referencing the HSI for a rate as what you posted is not what I have experienced to maximums albeit traffic dependant in some cases so far.

___A quick trip in a spare and not setup 2010 Prius-III around Rochester, MI while at the HS 250h launch a few months back.


The 83.7 was after coming off the Interstate to a stop and than making a corner when I snapped
the pic. The aFCD was at 79.x mpg and Avg speed was 48 mph whenI exited. -- The 99.9 mpg
was with an avg. speed of 25 while I circled the motel parking lot in EV to find a place to park.


___Here is some more while coming through the morning Chicago Rush headed home...


8-miles past the Circle (downtown Chicago)


9-miles


12.7 miles


14.3 miles


16.4 miles


28.5 miles


44 miles


Final at home when filling up that night.

___Subtract the customary 6 for some reasonable actuals.


NAPA Valley FE challenge


An untimed challenge through stop lights, signs and Rush hour around Napa Valley.

___And subtract the customary 6 for a reasonable actual.

___All I am saying is be very very careful with how you present the HSI for Max or near Max FE. Right now, the Prius-II can dominate the Prius-III on the highway and around town in my few thousand miles with the 2010. I need some more time in one for the low speed stuff to figure out some decent rates and ranges and I highly suggest you spend some quality time in one as well. Until you begin to see these kinds of pics from those at PC having this discussion, I would be very leery as to what any of them have to say about near or peak maximums as the Prius-III is simply to new and none of us (imho) have the experience needed for a succinct document just yet. Any guide like the one you built already includes holes with the little experience I have in the Prius-III and I would prefer you wait until this gets sorted out by those that push the Prius-III to max either here or over at PC over the next few months.

___Good Luck

___Wayne

[ksstathead]

The document is out there, and it is useful for people to know not to accelerate into the power band, and not to accelerate ICE-off, etc. Furthermore, most Prius owners will not have Scanguage or CanView, etc. They need something.

That said, the caveats in the draft could be expanded to state that the best mileage may come from the lower end of the acceleration rates presented based upon the preliminary results of xcel. Also, that more work is needed and extra instrumentation will be needed to really max it out once the work is done.

Traffic and resistance to hypermiling will keep many from achieving elite mpg even after all the optimums are known. But no reason I see not to tell folks that there is a real drop off in the power band, etc. Mention avoiding cruising in the 42-45mph range?

It's very interesting when two fuel economy heavyweights slug it out...