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Do the mileage figures make sense?

Discussion in 'Gen 4 Prius Main Forum' started by kgall, Nov 25, 2015.

  1. kgall

    kgall Active Member

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    After looking at the national press material from Toyota, I don't get how the 2 eco can have 6 percent better gas mileage than the 3 and the 4, with only a few pounds difference between them, no difference in shape and as far as I can see the same operating machinery. On the other hand everything else is given the same mileage rating, even though the 2 has a different battery and the Touring models have bigger wheels.
    Do the engineering/mechanical types here have any insight?
    Are the mileage figures final?
     
  2. Mendel Leisk

    Mendel Leisk Senior Member

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    Different programming?
     
  3. JimboPalmer

    JimboPalmer Tsar of all the Rushers

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    Different tires
     
  4. energyandair

    energyandair Active Member

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    See this thread: Prius Eco 58 MPG vs Prius 54 MPG - What's the difference? | PriusChat
    At this stage I don't know that we have final EPA numbers and the impact of the possible reasons discussed for the difference are in large part conjecture.
     
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  5. Tideland Prius

    Tideland Prius Moderator of the North
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    It's 40 lbs between the Prius Two Eco and the Prius Three/Four.

    Tires are different. Toyota is using a specially designed ultra LRR tyre (I think it's called Dunlop Nanoenergy) and the factory tire pressure is 39/36 PSI vs. the Prius Three/Four that use the Bridgestone Ecopia line of tires with 36/35 PSI as the factory pressure settings. That's probably the biggest difference (followed by the weight loss). Highway mpg is up 3mpg and I'm pretty sure the rear wiper doesn't account for most of it so it has to be the tires. The aerodynamic bits are the same between all models.
     
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  6. The Electric Me

    The Electric Me Go Speed Go!

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    I think I'd feel somewhat mislead if I bought a Prius 2 Eco, then discovered that the majority of it's gas mileage benefit came from it's tires. I mean, tires are going to wear out and be replaced.

    Does that mean to keep the most of the benefit I'd have to commit to those particular tires for the life of the vehicle?

    If I put those tires on any other Prius, including mine, would I get near the same mileage?

    I think if you are going to offer something as a trim designation or model "difference" than the difference should be something more substantial to the vehicle than simply a different set of tires.
     
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  7. civicdriver06

    civicdriver06 Active Member

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    Two Eco has no rear wiper ?
    We won't get Eco in Germany anyway and for all I care they can keep it .
    I rather have all the bells and whistles and at the same time very good mileage !
    Besides didn't Toyota say that the rating they published were their own numbers achieved on the new more agressive EPA test cycle which doesn't even come into play yet ?
    If so I guess mileage will even rise on all available versions testet on the old still relevant test cycle !
     
  8. kgall

    kgall Active Member

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    energyandair: Thanks for referring me to the other thread. I was looking for something like it and somehow missed it.

    TidelandPrius and jimbopalmer: The tire theory makes sense. Unlike Electric Me, I guess I don't feel ripped off if a benefit largely comes from tires. And I can attribute at least 1 mpg difference--maybe as much as 2 mpg less--to changing my Gen 3 tires from the OEMs to Continentals with Ecoplus.
    So, do we have any idea why the new superLRR tires will only be on the 2 Eco? You would think they would put them on higher priced models too.
    My first hypothesis might be that traction or something else is sacrificed to get the very low rolling resistance. (My new Continentals are much better as tires, even if they are worse on gas mileage.)

    Danny: see if you can get a comparison ride in the 2 ECO vs. 2 or 3 to feel the difference in the tires.
     
  9. JimboPalmer

    JimboPalmer Tsar of all the Rushers

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    LRR are thin, expect shorter life and less traction,
     
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  10. spwolf

    spwolf Senior Member

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    urgh, tires are one of the most important parts of gas mileage of any "eco" model from any manufacturer. You need to read up more, I have no idea why would eco tires lead you to be mislead... interesting train of thought. What if you remove windshield wiper as well?

    I mean Eco model is 2nd cheapest model in the lineup... it is not $10k more than others.
     
  11. The Electric Me

    The Electric Me Go Speed Go!

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    I know tires are a big part of creating fuel economy.

    But YES, if something is being sold and advanced to me as an "Eco" model, I kind of expect that the fuel economy is being created by something MORE than just a different set of tires.

    I suspect and I think it's just the truth that it's the tires and "other things" such as less weight.
    Otherwise, when those tires wear out? You are going to get a lot of disappointed Eco Model owners who suddenly get a big drop in MPG when and if they change to any other tire.

    And evidently the rear wiper on a Prius is a economy killer.....who knew?

    If those tires can near alone create that great a difference in fuel economy? And they are 1/2 way usable and descent? Then I want them on my "Non-Eco" model Prius.
     
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  12. Mendel Leisk

    Mendel Leisk Senior Member

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    Any speculation on why Toyota's producing this Eco model? To meet some mandated mpg target?
     
  13. The Electric Me

    The Electric Me Go Speed Go!

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    I don't feel "ripped off".
    On one level I don't care.

    But the rest of your comment is kind of my point. If it's primarily just the tires? Why even bother with calling something an "Eco" model? If we are talking 65lbs, and the absence of the rear wiper, and these "magical" LRR tires, why not just put those tires on ALL the Prius and let the MPG chips fall where they may?

    My primary concern would be people making the "Eco" model choice, then when changing tires in X amount of time, feeling disappointed if their mileage drops more with a tire change than for the rest of us, that start with "standard" Low Rolling Resistance tires.

    Last incarnation I similarly wondered how Toyota was able to make the same MPG claims across the Prius line when the Solar Sunroof model was heavier.

    So maybe the "Eco" model designation has more to do with Toyota avoiding any trouble with the EPA, when it comes to minutia differences in reported MPG.
     
  14. JimboPalmer

    JimboPalmer Tsar of all the Rushers

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    Why are not all Prius ECO? The battery may not work below -29, that would eliminate several states and provinces. The lack of a rear window wiper limits the attractiveness in western Washington and Oregon, as may thin tires if they hydroplane.

    I expect it so sell well in southern California
     
  15. HGS

    HGS Member

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    For a buyer not doing their homework, purchasing an ECO may not be wise if living in an area of the country where a rear wiper is a safety item. One would think Toyota would only offer that model in such places as Southern California.
     
  16. fuzzy1

    fuzzy1 Senior Member

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    More likely to meet the expectations of some customers.
     
  17. The Electric Me

    The Electric Me Go Speed Go!

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    So your speculation is that the "Eco" designation is being applied so Toyota can focus geographical availability?

    Those places where it drops below -29 degree's may be problematic for any Battery.

    Since it can rain suddenly and with force in nearly any environment, even occasionally Southern California, I would expect these "magical" tires meet some minimum standard of wet traction. Otherwise Toyota and the tire company would be heading for headlines they nobody would want to see.

    And I live in Oregon, and it certainly rains a lot. I can say the times I use the rear wiper are pretty rare.
    I'd say the benefit of a rear wiper comes with the ability to wipe off dirt and grime as much as using it in actual rain.
    In fact in rain? I hardly ever use it.
     
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  18. spwolf

    spwolf Senior Member

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    I am having really hard time understanding you. You know you can buy those same tires, right? You would feel disappointed because different tires give you different mpg? We already know it is not just the tires, but several other things including tires, higher pressure, better aero (rear wiper) and less weight.

    Once again, Prius Eco is cheap Prius. Of course you can add the same tires to more expensive Prius. You are acting as if you have to pay extra $10k for Prius ECO and that you can "cheat" them by spending $600 on set of tires. Makes no sense at all.
     
  19. The Electric Me

    The Electric Me Go Speed Go!

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    Yeah, I've pretty much said that all along.

    And I'm having a hard time why you seem so adversarial to my opinion and simple thoughts on the manner.

    I don't care what the cost difference is...either cheaper or more expensive. Not really the point. The point is Toyota is presenting an separate and distinct ECO model.

    I didn't start this thread, and if you'll notice, the title is "Do the Mileage Figures make Sense?"
    The speculation that I didn't present or advance, is that MOST of the gain comes from the tires. I have no reason to believe this isn't true.

    OK then, I think it fair to ask the question are tires enough to designate an entire vehicle as being a specific "ECO" model?

    I also think it fair to speculate that "IF" the tires are what are creating the greatest portion of difference in fuel economy, you might have a fair number of ECO model buyers that eventually change tires to some other more standard version that are surprised by the sudden difference.

    Even if you disagree with these opinions and thoughts, what's so hard to understand?

    Like I already said, if these tires are available? Depending on their real world evaluation I would certainly consider them based on their supposed MPG improvement.

    However, in all the threads about tires within Prius Chat that I've read, I've never had anyone in North America recommending Dunlop Nano Energy. Michelin-Yes....Escopia-Yes-Conti-True Contacts-Yes. Some others, but I would feel relatively confident in saying "Nano" tires at this point if available in the USA, certainly haven't been a popular choice.

    If they are succesful I welcome the success. For EVERYONE.
     
  20. HGS

    HGS Member

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    The only thing I know from experience is that driving while heavy snow is falling and seeing out the rear window requires a rear wiper. But, you are right about rain. I don't use the rear wiper usually while driving in rain.