The myth of pulse and glide

Discussion in 'Fuel Economy' started by Chuck, Jul 11, 2009.


Has pulse and glide worked for you?

  1. Yes

  2. No

  3. What is P&G?

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  1. diamondlarry

    diamondlarry Super MPG Man/god :D

    Yeah AE, until you can do 100+ for a day's worth of driving, or a whole tank for that matter, I'm going to have to assume that you've been spending time with your face too close to your tail-pipe.;):D
  2. AlmightyEngineer

    AlmightyEngineer Engineering First!

    What is the reputation 'hypermiler' is earning? Is it a relaxed, calm, smooth driver or has it become associated with "ice vests," "turning off engines," "drafting trucks," and "pushing cars in the heat on the street?"

    The reputation of 'hypermiler' is enough that I prefer the term, efficient driver, since it is not burdened with the bad-boy reputation of extreme driving. Boring, old-man, efficient driver, that is me.
  3. Chuck

    Chuck just the messenger


    Saying we drafted semis all the time over and over again, does not make it true - it just makes you look absurd repeating these falsehoods.

    I'm not that great in math, but you call yourself and efficient did you get your engineering degree by saying 52mpg > 100mpg?

    I was thinking of you when I saw this
    Last edited: Jul 12, 2009
  4. ILAveo

    ILAveo Well-Known Member

    Shoot, you just needed to ask. Ford Ranger 2.3L 5 speed manual transmission 30-50 mph P&G on level ground nets 55-60 mpg, steady state 35 mph 45-50 mpg.

    BTW, last I checked this was an advocacy website, so I think your disappointment in the experimental standards here is a bit misplaced.
  5. diamondlarry

    diamondlarry Super MPG Man/god :D

    '07 Prius, 19-35 mph with an acceleration rate of 25-30 (target of 27.5) "gps" X-gauge
  6. cpeter38

    cpeter38 Right Lane Dweller

    Contour SVT - Last tank - 60.09 MPG. NEVER drafted a truck.

    52 mpg on a Prius?? You're not efficient at all.

    Not even close.

    I'll happily tell you that I push my car about 10 ft every morning - so I can judge my start time. I don't want to impede traffic and I live on a very busy countryish road in metro Detroit.

    Ice vests? WTH drugs are you smoking??

    Turning off the engine?


    Why not?

    I get a lot better FE than you and I'm giving an old beater vehicle a second life instead of dumping a lot of energy and materials into a landfill and recycling the metal.

    P.S. My standard P&G is 40 -> 47 MPH or 50-57 MPH with a targeted LOD of 78%. If the engine is cold, I drop my LOD target by approximately 10% until I achieve a coolant temperature over 160F.

    P.P.S. I think you might want to reconsider your title of "AE". Pretty graphs don't substitute for results and the willingness to learn. You have obviously failed at both of the latter.
  7. iamian

    iamian Well-Known Member

    I do not find anywhere in his post the quote you make here???
    Did AlmightyEngineer ever make this claim?

    I also do not see how it effects the relevance of the data presented???

    I will say the data is far from conclusive ... but I do appreciate that much attention to detail and presenting the data... and I would encourage further exploration of the data and details involved.

    MPG measurements are nice... but it is still just one number ... and there is far more data to had and learned from a wide variety of other numbers for additional data ... RPMs, Engine Load , type of fuel , Temperature , Tire Pressure , Altitude , etc...etc... MPG is useful ... definitely ... but MPG only reports the net result of all the other thousands of pieces that go into making up that single MPG number.

    For an example:
    As to why the personal MPG number is not related to the data , or to someones personal knowledge of the issues ... If a professional engineer who was involved with the design and building of the Prius ICE tells me about that ICE ... Even if he personally drives a Prius and only get 30MPG ... he still knows more about that ICE than someone else who is not an engineer , even if that non-engineer is able to get 100 LMPG ... and if the non-engineer with 100 LMPG disagrees with the actual engineer who actually built the ICE about that ICE ... than MPG or not ... the 100 MPG guy is wrong ... and the 30 MPG guy is correct.

    I 100% agree... conditions will vary ... different cars behave differently ... different routes give different conditions ... and different driving methods can return different results.

    Take the best from each ... learn from all of them ... learn from everyone you can ... even if they do not get better MPG than you... they might still have knowledge and data to share that will help you to improve.

    To each their own.

    I'll look at the data he is presenting for what it is... and that data is far from conclusive ... but the data and conclusion he pulled from it are far more relevant to me.

    To me his personal MPG means next to nothing compared to weather the data itself is correct ... and weather the conclusions are well founded and follow from that data.

    And as he already posted ...

    Not that it effects the validity of the data presented either way.
  8. cpeter38

    cpeter38 Right Lane Dweller

    It sure looks to me like he is averaging 52 MPG - that's his claim.
    As to whether or not he thinks he is a good driver, I'll let you judge that yourself from his posts (although in my eyes he has a completely unjustified opinion of himself as an "Almighty Engineer").
  9. JusBringIt

    JusBringIt Be Inspired

    I'm not your first grade teacher and will not try to explain what mr. "Almighty Engineer" means by "signature 52mpg"

    Proper term is "affects". Learn to use your terms correctly.

    I could copy a bunch of junk anywhere off the internet, post my FSP getting 80mpg over 20 miles and some graphs that are poorly created to convince some novice that I know what I'm talking about, I don't have such time to waste.

    MPG is the cumulative result of all those different environmental and induced factors summed up to let you know what has been happening over your trip or tank. To a certain extent, you the driver will be able to distinguish how much of an effect each particular factor had on your MPG.

    If you think one engineer designs the entire engine then you are gravely mistaken. Look around on this website and you will find information concluding the engineers of the prius looking for advice on how to drive the prius to achieve max mileage. Ask why Ford contacted Wayne so they could exceed 1000 miles on a tank in the Fusion.

    This I agree with, however, when someone is spewing "hard facts" about something that I ALREADY KNOW and disagree with by empirical examination, I tend to feel the need to share the truth so that others are not misled.

    The data is far from conclusive, but the conclusion he pulls are relevant??? I must be in the matrix or some other universe because this doesn't make sense as a standalone statement.

    Cumulative mpg is more important than any single tank or instance of mpg. Repeatabilty with credibility is even more important.
    He does not have the latter, so the former falls in the same bucket.

    For the record, I've studied with multiple engineers, and an engineer myself. Granted I'm still learning and will be for the rest of my life, there is obviously nothing to be learnt from the previous post by mr. "AlmightyEngineer".

    Good luck.
  10. ILAveo

    ILAveo Well-Known Member

    Sounds like you spend too much time evaluating labels placed on people, but probably missed on that one. I'm pretty sure that hypermiler isn't what most people have in mind when you say "bad boy reputation."

    Though it'd be kind of cool I guess -- Be careful of me, I'm a threat, I get reeeeeally good gas mileage.:p;)
  11. R.I.D.E.

    R.I.D.E. Well-Known Member

    Two sides to every coin.

    One side sacrifices everything for mileage, regardless of the consequences and any effect on the overall flow of traffic.

    The other side recognizes that there is an increased level of danger in operating any vehicle outside of what the average driver considers normal conditions.

    Absolute mileage for me could be close to 100 MPG, if I wanted to suffer the consequences of the inconvenience I would place on other drivers, which in some case could be catastrophic, or the additional wear and tear on my vehicles that would result from operation beyond the design parameters of the vehicle.

    I live somewhere in the middle. My tires are at sidewall max. I usually average 35 MPh or better, in most cases 40 MPH or better. I try to be the least impediment to other drivers on the road and it usually cost me some absolute mileage.

    Today I drove to Richmond and back, averaged 69.5 MPG. Average speed was probably 55 MPH on the highway. Could I slow down and get 80? Yep. Even more and get 100? Yep.

    Drove into heavy traffic to meet the family for dinner. Got on the Interstate and went 60-65 MPH, even 70 MPH to get into the left lane because my exit is a left off the road. Even at that speed I have someone tailgating me at 3 car lengths, so I put the left front tire on the left line to send the jerk a message. I had to turn left and he could easily have passed me or just moved to the right lane while I safely negotiated the left turn off the Interstate, the only left exit on 64 from Hampton to Richmond.

    Get off my arse!

    Will I ever be the best hypermiler here?

    No Way.

    Will I make the best of my self chosen compromise.

    As good as anybody here.

    Current average distance driven for our 3 cars is about 2300 miles per month. Current average mileage is in the neighborhood of 50 MPG combined. Last tank the wife beat the EPA highway rating for her Rogue at 27 MPG. The Echo is at 52, and the Insight is at 67 with a CVT.

    That's about 46 gallons of fuel a month, round it off to 50 and $2.50 per gallon and you are spending $125 per month on fuel. My property taxes are over $200 per month. I could move to the mountains and live in a tent like a pauper, to save the $200 a month, but the wife won't let me, or at least she wouldn't go there.

    Pulse and glide works fine for me, I use it when the opportunity arises without affecting the traffic around me, and sometimes when I encounter a Moron who wants to tailgate me to send them a back off message.

    You see people the mileage you get is great, but the average speed seems to be lost in the equation. If I fall asleep driving 25 in a 55 zone and run off the road and kill myself, the mileage I got doing that is irrelevant.

    I guess I could shut my engine off to save .07 gallons of fuel in a 30 minute 20 mile drive, when I normally use about .37 gallon, in the Echo. I could try engine off coasting in the Insight CVT and spend thousands on a tranny.

    That would get me 65 MPG instead of 53. It would accelerate the wear and tear on many vehicle components, and its illegal in Virginia, and would be apparent to any police officer if he paid enough attention, so I don't do it for several reasons which I believe are significant enough to justify my decision.

    I run my tires at sidewall max 44 PSI.

    If I lived in a less populated area, with less aggressive drivers, and I felt comfortable with engine off P&G under those circumstances I would do it, and I don't feel the necessity to criticize others for their greater dedication to their effort.

    I do think that for people who come here to learn how to drive more efficiently there are limits to their willingness to make significant sacrifices in their effort.

    I also believe that a heck of a lot of those efforts can, and eventually will be made unnecessary by basic improvements in the way cars are designed, and we all should focus our energies on that component of engineering.

    Maybe the Almighty Engineer should work on a self hypermiling car, to save us poor peons from ourselves.

  12. Chuck

    Chuck just the messenger


    Have you really seen hypermiling first hand? The 3.5 years of your posts sound like most that condemn it - have not seriously done it and for irrational reasons, attack it.

    Seems like it disturbs you greatly that thousands are getting great FE. It may not be with the precision of a study at the EPA, MIT, or Standford, but it's so conclusive it works....your focus should be to explain "why" - not "if".

    Refrain from personal attacks - understood?
    Last edited: Jul 12, 2009
  13. AlmightyEngineer

    AlmightyEngineer Engineering First!

  14. iamian

    iamian Well-Known Member

    I was not referring to his signature... which still has nothing to do with the data presented.

    This is what you wrote:

    Where did he make the claim you are quoting?

    I have not seen him post this anywhere ... and when you put ... good results ... in quotes ... this makes your claim that this is his exact words he used ... Which I have not found in his posts.

    And what he gets for MPG still does not alter the accuracy of the data presented.

    thanks :)

    My mistake.

    ... so now ... please tell me where he wrote what you quoted. :p

    I agree that the data itself is not absolute ... nor conclusive.

    And of course pictures and graphs can lie and mislead.

    But if you think the data is faulty ...
    Where is the error?
    What do you think might have caused the bad data?
    Do you have different / counter data to present?
    Was Important data left out?

    If you do not disagree with the Data...
    What part of the analysis do you find in error?
    Was the test itself biased?
    Are the results present in a biased fashion?


    MPG is the net.

    If I have bad accelerating technique ... but my decelerating technique is great... one can offset the other... if my route is more MPG friendly it will also offset other errors ... if I fill up with E15 I will have lower energy per gallon compared to straight gasoline... If I park my car in the winter and only drive it in the summer that will also offset some of my driving errors by avoiding the low MPG season... If I add an oxidizing agent like Nitrous Oxide I can alter the effective power output from an engine cycle .... etc...etc... the MPG number does not tell me each of these factors ... it is the net of all of them... and it doesn't tell me what I am doing right or wrong ... just what the net result is from all factors combined.

    not at all... and you are very correct there are lots an lots of people involved.

    The example I gave was not claiming that only one guy made the Prius ICE... here I'll repeat myself and pick it apart a bit more.... maybe that will help.

    Notice where I write :

    He doesn't have to be the only professional ICE engineer working on it... but if he was one of those involved... then even if he gets 30 MPG in his own personal Prius ... he still knows more about the Prius ICE than a non-engineer even if that non-engineer gets 100 MPG... he might not know as much about driving techniques , or any number of other things ... but his lower MPG number still has no impact on what he does know.

    My MPG ... no matter what the number is... does not make my claims gospel ... I can very easily be wrong ... and someone else with lower MPG can very easily be correct... and if I am willing to look with an open mind I might learn something.


    maybe it is just my own personal preference here... but instead of just writing things like:

    This doesn't explain anything... this just shoots a guy down after he put some effort into trying to look at the data of the issue... and then present those finding to the benefit of other forum members.

    Maybe it is just my own personal preference here but ... I would rather see the counter study... the counter data.... if you've already posted it before and don't want to re-write it... just give the link.

    Explain where you think he made mistakes in his data collection ... or in the analysis of that data.... that kind of thing.

    Pointing to someone's personal MPG at best can only do one thing ... try and undermine their credibility ... and maybe they are not creditable ... but it still is a dodge / side step from the issue itself and the data and conclusions made ... to attack the character of the person instead of looking to see if there are flaws or errors .... in the testing method ... the data ... or the analysis... etc.

    That's my bad... here.. I'll try and re-write it to be a bit more clearly understood.

    He presented actual data... unless that data's accuracy / validity is being questioned ... then that data alone by itself ... has value to me.

    That data is relevant to this discussion.

    If the data is being questioned for accuracy &/or validity ... than someone should make another data collection set to check the data given... also the data very likely is not complete... is there additional data not yet presented that holds significant influence?

    The data is not conclusive ... conclusive data from testing of Pulse and glide ... would very likely fill several thousand pages of just raw data... I understand he does not have conclusive data... but he still has data.

    He makes conclusions from his analysis of his limited collection of data... his conclusions can very well be wrong... but those conclusions based on data he is showing ... have value to me... because we can go back and track where those conclusions came from.

    Even if the conclusions turn out to be all 100% wrong ... misplaced a decimal or something ... or whatever ... the beauty of the data collected is that we should be able to eventually go back and figure out where he had made the mistake when he made conclusions from the data.... and if we don't want to help him out by showing him where he made the mistakes ... than he still has the data and he can still go back and look at it again someday.

    So to me at least ... his conclusions and data which are being presented have value ... and more so than just saying he is wrong... even though I still find his data to not be conclusive ... and he does make conclusions that I do not think are properly supported by the data given.

    To the driver at the end of the day / year ... yeah sure...

    But my cumulative MPG as already stated above ... is the net of many many factors ... and will include things other than the single issue of interest being examined.

    This is not about all of the factors that effect MPG... this is just about P&G.

    He concluded from the data of one test:

    That is the result of the test he did.

    With different conditions ... or driving methods used for P&G ... it i very possible a different result would have happened... which is why a conclusive series of tests would have thousands of pages of raw data.

    A full tank or two or three of MPG ... could only be used effectively for a controled test ... if P&G methods and testing methods could be maintained for the entire duration of that test.... long term MPG numbers blur the details that we are trying to explore here in a targeted issue like P&G.

    Of course the test itself might bias certain testing methods ... which for example, has from time to time been a complaint of the EPA MPG rating system.

    Great ... glad to read it... :D

    So if you disagree with the small data set ... and minor study presented ... do what engineers and scientists do... setup your own test ... collect your own data ... present that data and the conclusions you pull from it... or provide a link / reference to where you have already done this work previously.

    to each there own...

    I'm not so quick to toss aside the work , and data presented.

    I think that it is better for everyone interested in P&G to better understand how and why things work under certain conditions ... and the more we collectively as a community learn and gather the better the community is as a whole.

    I think sometimes that means in order to get at more of those details ... we have to look at more of the details that blend together to get a MPG number... and the MPG number alone is just no longer enough in order to continue to learn and improve... eventually we start looking at RPMs, Load, SoC, tire pressure ... the Raw MPG number does not let us test these things by itself... we need more than just MPG.
  15. diamondlarry

    diamondlarry Super MPG Man/god :D

    Do we always have to understand why things work? I don't fully understand what makes up gasoline but, I know that if there isn't any in my tank, I'm not going anywhere. It's the same with P&G; does it really matter how or why it works? A phrase I heard many times during some business training comes to mind: "To get what others have, you have to do what they do." Or, "Listen to the ones that have fruit on the tree." Just my $.02 worth.
  16. Chuck

    Chuck just the messenger

    A really good technical person can explain things simply.

    Pulse and glide works, but moderately accelerating a few seconds, then coasting several times longer than the pulse. The internal combustion engine is complicated with so many things to keep it going and offering friction...coasting with the engine off elimiates that.

    Is that concise or what?
  17. cpeter38

    cpeter38 Right Lane Dweller


    I am a former engine systems engineer. Although I have had no personal involvement w/the Prius, I can say with some authority that just being "an engineer" involved in the design of a particular engine means close to nothing. Some engineers just "vote present". Some engineers are pretty good at designing their component. Others are really good at churning out reams of data that mean nothing. There are few engineers that are capable of gestaltism. Those engineers are worth there weight in gold!!

    AE seems totally incapable of understanding pulse and glide. He says
    Starting at 25 miles per hour, the cruise control "resume" consistently accelerates the car back to the set speed, 43 miles per hour.
    That sort of begs the question:
    What rate am I accelerating at?
    Of course if you really cared about the data and were not just intent on personally dumping on and insulting hypermilers, you would buy a SGII and KNOW what your LOD was.

    I mention the personal intent because you can read his intent from his avatar. No person, especially one who considers himself a "ALMIGHTY Engineer", could trot into a hypermiling forum without understanding the level of insult he is giving by both his words and his avatar.

    I could make data lie in many ways if I was that type of person. However, I am not a troll. I prefer to help people.

    I suggest we stop feeding the troll ...
    Last edited: Jul 12, 2009
  18. cpeter38

    cpeter38 Right Lane Dweller

    Here is my constructive input into this forum:

    My standard P&G is 40 -> 47 MPH or 50-57 MPH with a targeted LOD of 78%. If the engine is cold, I drop my LOD target by approximately 10% until I achieve a coolant temperature over 160F.

    Using this technique, I have achieved well over 250% of my vehicle's unadjusted combined EPA on E10 gas while driving in Metro Detroit.
  19. jimepting

    jimepting Well-Known Member

    Lets just shut this thing down. Wayne?

    The "data" might have been interesting if it was understandable. I asked several questions by way of trying to understand the graphs and the data points. No explanation was forthcoming. I must conclude that the "data" is meant to confuse, not inform. Therefore this is just a game. I'm off this thread for good!
  20. Chuck

    Chuck just the messenger

    AE will restrain himself - even if help is needed. ;)

    I strongly suggest that AE takes a break this weekend.

    This is not like the other places he has thrown firebombs - he is going to have to exercise some civility, respect and real facts.


    I did not understand some of this for awhile, but did not scream about some of the phenomenal figures some achieved. If reading up on it does not work, then a clinic might - as it did for me.
    Last edited: Jul 12, 2009
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