I fail to see the "extremeness" of laurie going 60 in a 65 zone on her commute or myself going 50 or a bit faster in a 60 well before rush hour (speed limit in the evenings)....and letting drivers pass freely in anyway possible.

Old saying: "Truth is the first casuality in a war".

The author of "Swift boating" applied to hybrid electrics is very comfortable using the same tatics starting this thread. Stuff like cherry picking techniques to give a distorted picture of hypermiling. Data is meaninful if the analyst is willing to accept the outcomes he might find personally undesirable should they occur. True research is the pursuit of truth - not the promotion of a POV which was clearly the purpose of this thread.

 

Hi Chuck,
If held at a constant speed, this is called driving at an efficient speed, which is different from P&G. It can be accomplished by using cruise control but it also illuminates the problem of a vague and imprecise definition of P&G. From the information provided, the P&G classification sounds like:

min-max(average)P&G
60-65(62)P&G
50-60(54)P&G

Do you have you any data comparing these P&G ranges with the equivalent average speed at a constant speed?

Ahhh, you must have your preferences set to start from the earliest instead of the latest posting. For those who start with the latest, the most recent in time posting in a thread, my first post can be found at:
https://www.greenhybrid.com/discuss/...67&postcount=1

(NOTE: click on the "!" and you'll get the URL for a specific posting.)

The facts and data speak for themselves, all misrepresentations aside. I am comfortable we've explored how the media and public perceive "hypermiler." Even the defenders have volunteered observations showing the problem. That is why I prefer the term, "efficient driving," to describe what we do.

We've also introduced a way to define P&G that is both compact and exact:

"minimum_speed-maximum_speed(average_speed)P&G."

This leads to empirical studies that can characterize when it works and when it doesn't . . . like with a wheels off hybrid (hint: it won't work.)

Bob Wilson

 

Actually Bob, I dont know if min/max/ave fully describes a P&G cycle.

Are the rate of accelleration or RPMs on the pulse important as is how the glide is performed (light throttle, some regen, Neutral, FAS....)?

Also, in the side by side (or one after another) comparisons of P&G vs CC, it seems like you need to have the start and end speeds match and the elapsed time (or ave mph) be very close for the test runs or you may not get a fair comparion. I suppose if you get enough P&G cycles in, then the end effects may not be big. I need to get out there an try it and stop questioning...

 

"efficient driving" may mean something to us on this forum, to someone who is reading what we are saying. however, in the real world i can see that many people who are NOT in the mindset of saving gas will be delighted to consider themselves "efficient" because they get where they are going as fast as possible, and "drivers" because they are behind the wheel.......

 

Bob,

Just want to let you know that it's not quite a year since I've used pulse and glide. On my 25-mile work commute, I've been getting 70mpg in the winter, as good as 91mpg in warm weather, but let's round that down to 85. It's 5-10mpg better than over a year ago. Take away the first two miles and the last two miles and I'm maintaining a relatively constant 50-60mph (over 21 miles).

I can popout my ScanGage and put in www.carchip.com to chart my work commute. I want to make sure everbody else knows the problem of generating a chart while doing a pulse and glide that involves an ignition cutoff (as you most likely know). If I cut the ignition off five times on my work commute, six charts are generated and only when the ignition is on. Later this year I might be able to overcome this problem as Mike Dabrowski has a FAS devise that allows Insights to cut the engine without stopping the 12-volt supply.

The highways are like a battlefield with varying and unpredictable conditions, so is it realistic to expect the ability to do a strict P&G from 24 to 36mph? I think we all make the best with whatever we are given. That optimium P&G range will vary even from Prius I to Prius II, etc.... Is this variance "art" or rather having a better grasp on all the driving variables?

The demand for graphs, data....isn't recording it in the GH or CleanMPG database a decent snapshot? It's real world data that is sufficiently accurate to make a case for hypermiling - many of the highest scores are by hypermilers.

Speaking of real world data, check out Wayne (xcel) hypermiling a Prius I There is quite a bit of information in it.





...from this article

Try it Bob, and compare your results against...


That review should make it clear Wayne has no adversion to driving a hybrid and using it's robust fuel saving tools. Wayne has made the most in a non-hybrid, just as you have in a Toyota Echo - Bob.

There is no reason why the atmosphere could be less adversial on such threads. I think everyone here is after using less fuel, less emissions. Just evaluate it with a candid mind before making a judgement.

 

Hi Chuck,
This makes a lot of sense and includes some technical data needed so others can follow. BTW, there is a sharp knee in the NHW11 Prius performance around 65 mph and that becomes the effective, high-speed limit for good mileage. I find it interesting that you're running just under that speed too. The NHW20 Prius has a slightly different characteristic above 65 mph.

Perhaps you could 'wire OR' a 12 volt lantern battery with a pair of diodes? This would give uninterrupted power to the data recording device. What surprises me is you have to manually shutoff the ICE?

That is why controlled experiments are so important. Away from traffic, a chart comparing P&G with steady state answers the question of whether it is even worth while.

It turns out there are specific cases where P&G makes sense and others where it doesn't. It is model specific. This is where a graph can quickly lead to insights and avoids attempting to get more for a given technique than the engineering supports.

For a population study, GreenHybrid is great but for specific performance improvements, it is too coarse. Light airplanes have performance charts that are critical to safe operation and I'm just sorry we have to make our own for our hybrids.

I can appreciate the effort needed to generate a given MFD set of values but snapshots of MFD don't really show how it is done. A reference to the article is all it takes. BTW, my first chart was MPG vs. MPH and remains useful because it shows specific techniques and speeds and the results. It is a road map to efficient driving.

Bob Wilson

 

65mph is also the upper bounds in good fuel economy on the Honda 5-speed Insight - lean burn cuts out at that point.

Scangage and CarChip go in the OBDII socket....it would take some research to find out which pins supply the power and how much voltage.

The pulse and glide I describe is reaching a speed, then coasting with the engine off (the HSD have their own version...). The engine has so many parts generating friction and simply consuming a small amount of fuel to maintain running, that a glide of significant length will improve fuel economy.

 

if someone is new to this type of driiving, do you really think that pages of charts are going to be helpful? what is the purpose, and since they only seem to apply to the prius isn't that limiting their value? not everyone has the time or inclination to graph their driving to such a degree, but they somehow still manage to turn out tanks that are far above the EPA ratings. and isn't that part of the point?

 

It isn't that individuals need to plot the data but rather once plotted, everyone with that model car can use the data to drive efficiently. It is what the EPA sticker should be, a set of useful graphs on how to drive that car efficiently.

What has been lacking are folks willing to do the graph for their fellow drivers.

Bob Wilson