Power Mode anecdote

Similar terrain is not a good enough of a test to really say anything regarding the above MPG assessments. The difference between 50mpg and 48mpg is very small and there could have been any number of factors fudging the results. I'd suggest doing the same uphill run a few times in power mode then a few in Normal mode within a short period of time so as to minimize variables. Otherwise not much can really be said from your original results because the variables were unknown and you were not even on the same stretch of road.

 

Well, I used the word "theory" since the data set is far too small for proof and I realize there are many variables in play. But for what it's worth, I had a passenger (200lbs) for the ski trip and the rest of my mileage was just me with no real cargo. And obviously the ski mountain was a bigger altitude change than my other driving.
So, anecdotally, there might be something to it.

 

In my world a theory is a pretty strong word.

I look forward to seeing more data. Thanks for posting your experience.

 

duplicate post

 

Yeah, the word "theory" is supposed to stand for something with a lot of supporting evidence without necessarily having a mathematical "proof".

I should have used "hypothesis" or something similar. e.g.: the "Hypothesis of Intelligent Design" is a far more accurate description.

My testing today determined that driving on a flat tire is REALY REALLY BAD for mileage...

 

my "observation" today was that when pulse and gliding, where the pulse was into the PWR range of the HSI display... my mpg's for this tank increased from 46.5 to 47.9 over a 40+ mile drive.

my "theory" is that "Power Mode" makes it easier to achieve and optimum "pulse" when pulse and gliding, which increases MPGs.

 

FWIW, I was at the aforementioned Detroit event but I don't think I was in the group when questions about the power mode were asked. (We were divided into three groups, each of which got some time w/Otsuka-san.)

Four points:
- There was the issue of a language barrier since the chief engineer's native language is NOT English. The vast majority of the attendees didn't know Japanese.
- There were lots of us (50+) and the time was somewhat limited. Also, I think all of us wanted to be respectful of not lingering on any issue too long since others had questions too.
- IIRC, it was mentioned that at point 2,000 engineers were working on the 3rd gen Prius. It's mentioned again at http://priuschat.com/forums/prius-h...er-otsukas-media-presentation.html#post819730 and 2010 Prius driving review-preview @ the Prius owners group. It's simply not possible for one person to know everything about the vehicle and be involved in every single decision.

I haven't looked at the 2010's service manual, but if you look at what's in the 2nd gen's, oh my! It's a hell of a lot of work to engineer, test, and manufacture a car.

- The 3rd gen Prius could've undergone calibration/subtle design changes w/respect to throttle calibration and mode behavior between January and when it shipped in the US.

 

Good point - the opposite may be true for longer trips with fewer stops (warmer engine sooner by using pwr mode).

 

Anecdotally, I’ve experienced something similar – on my bicycle! Getting a running start on a hill (accelerating into it), seems to result in considerably less leg pain and heavy breathing than trying to maintain a constant speed from flat terrain to the hill incline.
Part of the effect may be the ability to run in a higher gear for longer, but the running-start advantage seems to be there even on small hills that don’t require shifts. I often ride with someone who sets a pace that is even slower than my usual one. Hills that I almost don’t notice when driving at speed become real work when driving slowly.

 

In "pulse & glide", ECO mode is easier for maintaining the glide - and may be more aggressive about shutting off the ICE while moving. (it IS more aggressive about shutting off the ICE at stops) You have to use a heavier foot for the "pulse", but it works out the same overall.

And I am still not convinced that the 2nd half of the pedal is exactly the same in every respect - I suspect the HSI may change in the different modes, and the "feel" is different to me even when pushing fairly hard on the pedal. I might concede the pedal feel as psychological, but the HSI seems to enter the red sooner in ECO compared to PWR - and I think the CVT might be behaving differently too.

 

What I was told in Detroit was this: "Full power is available in all modes, with most of the difference in the first half of the pedal."

I am slightly paraphrasing, but I don't believe there was ever a claim that the second half pedal response is exactly the same, only that full power is available if you need it.

Tom

 

That sounds more like the way an engineer would respond to a non-engineer.

So:
1) When the gas is floored, full power regardless of which mode.
2) Any other differences (no explanation) would be more pronounced in the first half of the pedal.

I haven't floored it yet, but at least it's good to know that you wouldn't have to switch modes to get full power - just "put the hammer down".

As for the second item, I definitely agree it's more pronounced in the first half of the pedal - but would love to know exactly what is going on in both halves... Right now I'm not entirely sure what is for real and what is just in my head (that applies to many things other than the Prius, but for the purpose of discussion we can confine ourselves to just the car).

 

I remember reading somewhere that in ECO Mode the throttle body is limited to 85% of "wide open" which helps reduce fuel consumption.

 

At full accelerator pedal position, the power becomes 100% on any mode.
http://priuschat.com/forums/gen-iii...e-explain-eco-mode-gen-iii-2.html#post1037726

Ken@Japan

 

Hi Ken - if that's official Toyota info, can you ask your source exactly what else is happening in the different modes? Many of us are seeing other differences (like ICE shutdown/startup) and don't know what else might be real vs subjective.

 

It is part of the Toyota's official New Car Features document placed by Hobbit.

AFAIK,
The ECO mode saves the A/C (both cooling in summer and heating in winter) usage for better fuel economy.

Ken@Japan

 

Ken, I'm not sure I see anything on your graph that indicate the throttle body position at various "accelerator pedal openings?"

What does your graph mean by "motive force output?"

What I do see from your graph is that for all "accelerator pedal opening" positions except for "pedal to the metal," the "motive force output" is greater than normal in PWR mode, and less than normal in ECO mode.

In real world terms, I experience and the graph confirms, for an equal accelerator pedal opening, PWR mode is faster than Normal which is faster than ECO.

Edit: I hope no one actually drives their Prius with the pedal to the metal!

 

It is not my graph, but Toyota's.
Prius is "drive-by-wire" system and there is no direct relations between "engine throttle openings" vs "accelerator pedal openings".

The "motive force output" is used for driver's power demand input to the Power Management ECU converted from "accelerator pedal openings".

When "motive force output" is small, Prius is driven by motor only.
When "motive force output" exceeds the 50% level of the HSI screen, Prius engine starts to reflect more "motive force output" demand.

I think your observation is correct.
100% "accelerator pedal opening" causes 100% "motive force output" in any mode.

Ken@Japan

 

I think Americans are obsessed with the idea of having a "turbo boost" button....