MPG ratings for PHVs are stupid

Discussion in 'Gen 1 Prius Plug-in 2012-2015' started by mozdzen, Jan 21, 2013.

  1. usbseawolf2000

    usbseawolf2000 HSD PhD

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    Yes, I know that. I am sure Toyota engineers took account of that.

    Ford plugin engineer has this to say:

    Ford has seen no durability problem with its battery pack from hot soak itself, Portalatin told AEI. So long as the vehicle is parked, peak temperatures in the battery compartment don’t affect battery capacity or longevity. Once the Energi is in use and the A/C is turned on (which can be assumed in very hot weather), pack temperatures quickly lower to an acceptable level.​

    Electronics diverge in engineering Ford's hybrid C-Max and plug-in Energi
     
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  2. drinnovation

    drinnovation EREV for EVER!

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    You cannot conclude that charging twice a day covers 40%.. since you don't know the time difference between trips.
    If my wife goes shopping 10 miles away, its 2 ten mile trips, with maybe 20min inbetween. If she stops at the post office, a drug store, plus two groceries (which she frequently does), its 4 "trips" of 2, 4, 4 and 10miles with stops maybe 2 min, 5min, and 20min.. Good luck getting your charges in that..

    Since you know nothing about the per-trip data's distribution in time, you cannot draw any conclusions about how much a difference providing two charges makes.




    +200!

    MPGe is not stupid.. people who mis-use it are stupid. However, I think its names leads to markeing hype intentionally misleading people. The decision to list MPGe separate for EV and MPG for ga mode is the problem. They should list all 3 CD mode range, MPG and then finally some combined MPGe for "average driving" (combining gas and EV with UF) and require them all. Maybe it should be 5.. requiring Highway and City.. to stop that abuse as well.
     
  3. Smurf1000

    Smurf1000 Junior Member

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    I went from 15 MPG to 40 MPG to 150 MPG while averaging 12,000 miles per year. You do the math....

    It doesn't matter how many KWH I used, as I have solar panels that create more energy in a day than I use in my PHEV. I charge at night, off peak, putting no additional stress on the grid and using excess capacity from the grid. (A little known fact is that the grid generates more electricity at night than it uses, so drawing on that excess capacity does not burn additional fossil fuels). During the day, when the grid needs power, not only am I not charging, but my solar panels are sending power "to" the grid.

    It also doesn't matter to me how many KWH's because 100% of the fuel used to make those KWH's came from the US or my solar panels....

    It doesn't matter how long it takes to charge because:

    1. It charges at the same rate as any other EV or PHEV (except Tesla).
    2. I plug in at the end of the day when I come home, and always have a full charge the next morning.

    On many occasions, I still have some charge left when I get home. If I need to go back out, I can top off for an hour or two and can go back out in the evening without using gas. (Reminder: it is cheaper to charge at home than at a fee based public charger)

    It is clear to me that you don't actually own a PHEV.......
     
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  4. mozdzen

    mozdzen Active Member

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    My wife drives the PiP and may even charge it 3 times a day. She does not have a 9-5 job where she has to drive to a specific location. But the activities she is involved with along with the domestic shopping allow for the multiple chargings. If she didn't have to do a once per week 100 mile drive, she'd be getting ~250 mpg with the PiP. As it is, she still averages ~100 mpg and keeps a ~42-58 EV to ICE mile split.

    I've (We've) never plugged in anywhere but home. Don't see readily available places and the fee for KWh is too high in my opinion.

    Why do you say that? We are getting 42% of our miles with the PiP in EV mode. A trip in the morning and then back home. A trip in the evening or afternoon and then back home. 42% is easy. Would be a lot more except for that dang 100 mile trip 1x per week. Again, the ratio can vary widely based upon the use of the car.
     
  5. lensovet

    lensovet former BP Brigade 207

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    i guess i should repeat myself.
    can we get back on topic please?
    I go to this page (which doesn't have HAPI yet): New Plug-in Hybrids
    I can clearly see the following:
    First, there's a row labeled Driving Range (miles). From it, we can see that the C-Max and Fusion hybrids have a 21-mile EV+Gas range, while the PiP has an 11-mile EV+gas range. Further, the C-Max and Fusion plug-ins have a little (i) icon next to this number, clicking on which brings up the following message:
    So in the case of the Ford Plug-ins, the EV+Gas range is really just the EV range, while for the PiP, it is indeed an EV+Gas range.
    Finally, for all the cars, there's a row labeled Miles per Gallon (MPG), which shows the mpgs in HV mode, as the OP wishes.

    I'm not sure what else there is to discuss here, except perhaps the following: the EV range number is very difficult to evaluate, much more so than MPGs. Why? Because, especially with the PiP, there are so many factors that determine whether the engine fires up even in EV mode that the numbers could be seen as meaningless.
     
  6. Smurf1000

    Smurf1000 Junior Member

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    This is why I love all PHEV's....

    We have now made the jump from 50 MPG to 100 MPG..... and beyond...

    I believe you drive a PHEV, but I still don't believe that Beowulf2000 does.......
     
  7. john1701a

    john1701a Prius Guru

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    Have you noticed how Toyota under-reports benefit of the plug? Their subtle approach has won over many consumers throughout the years... which is quite different than the hype from some others. I suspect it will work well for this Prius too.

    Anywho, HV miles also use plug-supplied electricity. But since the engine is running at the time, they aren't logged as EV. They just get dumped into the regular hybrid category instead, despite MPG being significantly higher than usual as a result of the extra electricity.

    That's why this thread discussing the merits of EV-range & HV-efficiency stir the responses we've seen. You absolutely must include other measures of performance, including the somewhat confusing MPGe rating. Ultimately, owners won't care, since their judgment of worth will come from the MPG experiences that follow the purchase decision... which is why some focus so heavily on that.

    In other words, use just a single measure, like EV miles, doesn't tell the whole story due to blending.
     
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  8. lensovet

    lensovet former BP Brigade 207

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    lol USB bought a PiP a couple of months ago. he's posted his stats here more than once. but again, i'm not sure how this is even remotely relevant to the OP's questions.
     
  9. Zythryn

    Zythryn Senior Member

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    Irrelevant, no single measure tells the whole story.
    Mpg doesn't tell the whole story for ICE vehicles.

    My counter to the OP is that MPGe does a fine job as a measurement. Could it be better? Probably. However, it is far from useless at measuring vehicle efficiency.
     
  10. mozdzen

    mozdzen Active Member

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    My feel good goal is this: reduce oil consumption (Smurf should like that).
    Why?
    1) it causes too much tension in the world.
    How?
    US Navy patrolling in the mideast with warships
    Nasty dictators get bankrolled.
    US trade deficit hurts our economy.
    China now needs to patrol with their navy so they can safeguard sea route to oil.
    Cities get smellier

    Maybe we don't make a big dent now, but you have to start somewhere. Plus we are helping Toyota along the learning curve and they keep improving the Prius with each new release.

    I'd love to get a Tesla Model S, but not when I could use that money to buy 2 or 3 Priuses.
    I'll agree that the regular Prius gets you the most bang for the buck. If you had a fixed sum of money to replace ICE cars for the sole purpose of reducing oil consumption, plug-ins would not be on the shopping list. However, it is fun to do a drive solely on electric.
    (BTW, I hate pulling in to quickie marts to fill up - one more advantage of any type of Prius.)
     
  11. drinnovation

    drinnovation EREV for EVER!

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    Nope.. never noticed any under-reporting. They claimed 15miles EV before the car was official then cut back to report what they are legally required to do with predefined testing protocols, and now say "up to 11 EV miles"

    We have virtually no way of seeing its not just what should be expected since there is no
    effective reporting of meaningful levels of real-world data. Even the MPG spreadsheet does not have anything like EV miles per day or per charge.. percent EV rates, as those mentioned in the post you cited, are not something Toyota, or other manufacture, comment on.
     
  12. john1701a

    john1701a Prius Guru

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    What is your point?

    The remark was about the information displayed in the car we drive, not a press release before it even rolled out or what is on the window-sticker.

    There were 4 measures of importance, each contributing to the big picture in their own way:
    • EV miles
    • HV miles
    • MPG
    • MPGe
    And of course, we need the values for gallons & kWh to fill in some blanks with.

    What else should we include?
     
  13. mozdzen

    mozdzen Active Member

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    EV miles and HV mpg at various velocities (mphs).
     
  14. RBooker

    RBooker Member

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    I think we should use gallons/100 miles in combination with cost/ mile. For PHEVs & EVs you could use zip codes to estimate the cost of electricity.

    Others have mentioned the problem with MPG.
    If you drive 10,000 miles/year calculate the cost savings of moving from a car that gets 10 mpg to one that gets 20 mpg versus moving from a vehicle that gets 25 mpg to one that gets 50 mpg.

    At this point, we need to employ a strategy that encourages owners in low mpg cars to purchase fuel efficient vehicles.
     
  15. Zythryn

    Zythryn Senior Member

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    Actually, I think that is a pretty good basic level of info to allow people to compare vehicles.
    The OP position is MPG/MPG ratings for PHEVs are "stupid".
    My position is they are not, that they provide good comparative information when used as designed.
     
  16. mozdzen

    mozdzen Active Member

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  17. drinnovation

    drinnovation EREV for EVER!

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    The point was replying to your Toyota hyping statement about under-reporting, and since you were vauge, as usual, I choose one interpretation related to this thread. I chose the one closer to the thread-- which was complaining about comapnies abusing MPGe in avertising.

    With respect to what the Car reports, the PiP (and Volt) report kWh ignores charging loss, so is that what you mean by under-reporting. That may make people feel better because it reports less than used. Is that what you meant? However, if you use the reported data to estimate MPGe.. it will over-estimate MPGe for either car. It takes external measurements to get good estimates of MPGe.

    The PiP also over-reports its MPG.. at least according to the PC chat spreadsheet, were there are 135 instances of over-reporting compared to the measured, and only 21 instances of under-reporting. (And the average amount of MPG over reporting is 2.5mpg)

    With respect to the OP, at one level I do agree that MPG and MPGe are stupid.. but I think they are stupid for all vehicles We should use G/100m (or L/100km) and kWh/100m (kWh/100km) with the latter measured from the wall. MPG is misleading almost everyone almost all of the time.
     
  18. lensovet

    lensovet former BP Brigade 207

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  19. Smurf1000

    Smurf1000 Junior Member

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    Amen..

    We could also add alternative fuels to that mix, especially for those that need the capabilities that low MPG vehicles provide and EV's/hybrids can't.
     
  20. john1701a

    john1701a Prius Guru

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    If you need clarification, please ask for it.