Do the mileage figures make sense?

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

  1. The Electric Me

    The Electric Me Go Speed Go!

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    I agree, with snow it's very good to have.

    Maybe Toyota should of named it "The Sunbelt Edition"?

    (It's a Joke....for those taking me too seriously).
     
  2. JimboPalmer

    JimboPalmer Tsar of all the Rushers

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    I expect it to differentiate those owners who need a fully functional car with excellent mileage from those who can accept a less functional vehicle with exceptional mileage Those owners need to be made aware that THIS Prius is not a cold or wet weather car without pundits claiming that ALL Prius are so limited..
     
  3. Tideland Prius

    Tideland Prius Moderator of the North
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    No rear wiper.

    Ditto. I think Toyota's hitting a point where mpg is harder to get and people expect more mpg from a Prius but at the same time, there's another group that expects more features (which adds weight). I suspect the Gen 5 Prius will have to use some weight reduction techniques and Toyota is praying that the costs comes down by then. There was a report earlier that they considered using an all-aluminium monocoque for the Gen 4 but scrapped the idea because of cost. (Or rather, how much the consumer is willing to pay for the exotic body). If CFRP can come down in price, Toyota might be able to do what BMW is doing with the 7 Series - use CFRP as a core and attach high and ultra high tensile steel and aluminium panels to it. It's a hybrid body on a hybrid!

    I think the mpg numbers are Toyota's own numbers but conservatively published. The numbers that the journalists are getting are in the high 50s and low 60s US mpg. Hopefully the EPA can "confirm" the numbers soon.

    I suspect it might be traction. LRR tires tend to have lower grip. There's already a difference in rolling between the Ecopias that came standard on the Gen 3 and my WRG3s. I'm using more fuel because the WRG3s have a more aggressive tread. They're LRR but not as much as the Ecopias. The Eco is probably a specialized model for those that want the ultimate in mpg. For most people who are ok with a compromise of great mpg and some comfort features and driving capabilities, the Two or Three will suit them just fine.

    It's optional on a 911 too because of aerodynamics. (And some would say it spoils lines ;) )

    Probably to show what's possible if people didn't want leather, moonroof and power driver's seat haha. (i.e. like a Gen 2).

    Also, it make the regular models look better. If Toyota only came up with 52mpg combined, there would be way more discussion now about how Toyota couldn't meet the target of 10% even though the EPA testing has changed.
     
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  4. bisco

    bisco cookie crumbler

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    i don't buy the weight being much of a factor. 65 pounds? the pip is 140 pounds heavier than the lift back, and gets about 5 mpg better. i believe it's all in the tyres. i don't think it's in the rear wiper either. maybe bob wilson will run some tests with and without rear wiper.:cool:
     
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  5. energyandair

    energyandair Active Member

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    To the best of my knowledge, thin (narrow) tires have an advantage in a wet climate as, all else being equal, the narrower the tire, the greater the resistance to hydroplaning.

    Reasons narrower tires have an advantage in resisting hydroplaning are:
    • the amount of water that has to be displaced for the rubber to meet the road is less,
    • the distance it has to go to get out past the tire edge is less, and
    • the contact patch is longer so after water is displaced in the leading part of the normal compact patch, more contact patch remains available to provide traction
    The internet contains varied opinions on the tire width and hydroplaning issue but from what I've seen, science and logic clearly support narrower is better rather than wider is better.
     
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  6. Mendel Leisk

    Mendel Leisk Senior Member

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    Maybe narrower tires improve traction, up to some threshold, go further and traction again starts to deteriorate. Just musing.
     
  7. fuzzy1

    fuzzy1 Senior Member

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    I took Jimbo's comment as referring to tread thickness, not tread width.

    I also strongly doubt that all else is equal with this ultra-LRR tire.
     
  8. Habnar

    Habnar Junior Member

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    They say they increased the tire pressures on the Eco trim. My experiments with increased tire pressures on my C has yielded a very bumpy, uncomfortable ride. Skinny round rocks probably won't yield a comfortable ride on the Eco either compared with bigger wider tires on the other trims.
     
  9. bisco

    bisco cookie crumbler

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    agreed. you'll have to be a real hyper hyper miler to want one. or just buy the tyres for the ride of choice.
     
  10. fuzzy1

    fuzzy1 Senior Member

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    Are you comparing to bigger wider 'soft' tires? If whose wide tires are turned into rocks, their ride will be even more uncomfortable than the skinny ones.
     
  11. Netcub

    Netcub Active Member

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  12. Mendel Leisk

    Mendel Leisk Senior Member

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    There's an apples/oranges statement in that link: 3.0 liters/100 km and 52 mpg US. Those two values are MILES apart; must be two test regimens.
     
  13. Maxwell61

    Maxwell61 Active Member

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    In some discussion before the presentation, i've mentioned the results of changing the stock tyres of my Auris with the Toyo Nanoenergy 2 LLR. And i noticed that the mileage % improuvement announced by Toyota for Prius IV looked similar to the one you get going from stock to LLR tyres, in my case 12% going from class E to A, as measured by testing on a german magazine comparative test, and confirmed by my own testing, as an average.

    So, i would say the ECO trick on Prius 2 ECO is likely mostly in the LLR tyres.

    So i tend to quantify the HSD 4 improuvement from the EPA comparison btw the non-ECO Prius IV and the gen3, with a good degree of reliability. That is combined 52 vs 50 mpg , 4%.

    The CLEAN MPG test, rather seems to point to some much more substantial improuvement of hypermiling possibilities for the Prius IV , but i see this is not been discussed or mentioned here. I do believe that will be the most interesting feature of HSD 4 , not the EPA results.

    About the improuvement brought by the ECO tyres, having those Prius ECO Dunlop no class, it's a bit difficult to be precise, but a 8-12% could be a reasonable mpg gain to predict. So, it should remain a very little effect for the contribution of any other difference btw ECO e non-ECO....

    Please notice that rolling resistance have a variable effect on MPG, very strong on low/intermediate speed, much less at highway speed were aerodynamic drag is prevalent.

    The good news is that very likely there's no need to buy that barebone ECO to get a better mileage, if you change tyres asap.


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    Unfortunately US does'nt seems ready to introduce such a tool for customers that is compulsory tire class; LLR does'nt mean a lot. Class values for rolling resistance coefficient it does.

    And it does seems in US you're not getting a lot of true and good LLR. As already discussed, in EU are appearing excellent "A" class tyres, that are "A" not only for rolling resistance but also "A" for wet driving. As an example, EU Bridgestone Ecopia 001S, double "A", fitted on a lot of Prius and Auris of our italian forum, are demonstrating their excellent results for every aspect.

    Unfortunately , due to the size, 225/45/17, i could'nt fit the Bridgestone on my Auris, so my only choice was the Toyo Nanoenergy2 , A class for rolling resistance, C class for wet conditions, actually a bit slippery. But so good for duration that 2 days ago, after 22000 miles, has been defined by my tire specialist "as new"....

    In no way, as someone is stating, an LLR must forcefully have poor wet performances or must worn out fast. Technology is here to sort problems, this is not a phisical limitation, is just material science.

    [​IMG]
     
    #33 Maxwell61, Nov 29, 2015
    Last edited: Nov 29, 2015
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  14. TonyWilkey

    TonyWilkey Member

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    The "Toyo Nanoenergy 2 LLR" is a summer tire. So is the fuel savings worth the cost of a set of winter tires? Will the Eco Prius be clearly labeled as coming with summer tires instead of "All Seasons"?
     
  15. giora

    giora Senior Member

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    Why creating a separate Eco model?
    My take:
    Remember the 6 months delay in reveal due to insufficient economy improvement?
    They had to come-up with something:)
     
  16. Mendel Leisk

    Mendel Leisk Senior Member

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    Both the 15" and 17" tires at the Vegas reveal were Bridgestone Ecopia EP422 Plus, no slouches for rolling resistance.
     
  17. KrPtNk

    KrPtNk Active Member

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    I don't remember mileage being mentioned as the reason for the delay. I thought the reason given was styling changes.
     
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  18. Maxwell61

    Maxwell61 Active Member

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    Are factory tires in US all seasons type? Not in EU, always summer tires. And of course you have to do some math to decide if is worth the change.

    Sadly "no slouches" does'nt help to reckon if there's room for improvement changing tires.. do you think you can get the RRC value from Bridgestone US? Just to place it in the EU/Japan classification system for RRc.

    Oddly enough, the absolute best LLR tire is available for Prius in japan (only) since 2012, the Toyo Nanoenergy 0 , in the 195/65/15 size only, a triple A.... 130$ each

    http://item.rakuten.co.jp/tire-worldkan-best/700100/
     
  19. Mendel Leisk

    Mendel Leisk Senior Member

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    North America is dragging their heels regarding rolling resistance ratings, sadly. But users report they're good, fwiw.
     
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  20. giora

    giora Senior Member

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    Well, I do...
     
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