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Ethanol gas vs milage

Discussion in 'Gen 2 Prius Technical Discussion' started by IABoy, Dec 8, 2010.

  1. IABoy

    IABoy Junior Member

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    Several people were discussing merits of regular vs ethanol blend as related to milage.

    In my mind the way to figure it would be how many MPG you got for the total money spent for the gas. My unscientific method would be to fill tank and note gas cost. Repeat several times to insure one type gas used. Switch gas types and repeat several times to insure this gas was being used. Bottom line would be you got this many miles for this cost or simply, cost per mile.

    Sound reasonable?
     
  2. kgall

    kgall Active Member

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    Yes, it does make sense, if you can locate two stations near you that each regularly sell either gas or gas/ethanol blend.

    But I would suggest this:
    Do a calculation of MPG for gas and
    MPG for gas/ethanol blend.
    That you should be able to do.

    What you really want to do is go a step further and figure out not just MPG but Miles Per Dollar of each fuel. That's a bit trickier, because the base price of each fuel may not stay the same over the time of the experiment.
    One thing you might do (if you are staying in one place for a time) is this: each time you gas up with one or the other, note the prices of both. Then you can average out the difference in cost over all the tanks, and compare the average percentage difference in price to the average percentage difference in MPG.

    Good luck.
     
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  3. David Beale

    David Beale Senior Member

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    In Edmonton gasoline with 10% ethyl alcohol (E10) is the same price as gasoline without. Both are available, though from different stations. It is more expensive to use E10 than gasoline with no ethyl alcohol in it. Mileage does drop with E10. I am sure you have read in the owners manual that the maximum ethyl alcohol content Toyota recommends is E15.
     
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  4. uart

    uart Senior Member

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    I've done a few MPG comparisons and though it's only by a small amount I find E10 does give less miles (by about 3%). Here in Australia E10 is about 2 or 3 percent cheaper, so the net result is not much difference either way.
     
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  5. BAllanJ

    BAllanJ Active Member

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    It seems all the pumps around here now have a sticker on them that says "May contain up to 10% ethanol" so it would be hard to do a comparison.
     
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  6. ken1784

    ken1784 SuperMID designer

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    scientific numbers...
    gasoline energy: 34.6 MJ/liter
    ethanol energy: 21.2 MJ/liter

    -> E10 energy = 34.6 X 0.9 + 21.2 X 0.1 = 33.3 MJ/liter
    -> 33.3 / 34.6 = 0.96

    The E10 has 4% less energy than gasoline.
    We will see 4% less mpg number.

    Ken@Japan
     
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  7. dhancock

    dhancock 2 Prius Family

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    I live in NY and often travel to Maryland (and also Minnesota). NY switches over to a winter blend earlier than PA & MD (or Ohio for that matter). I see the change in mileage (on the MFD - as you can't trust what goes into the tank due to the variability introduced by the bladder). It does seem to be in the 3-4% range.

    So I agree with your conclusions.
     
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  8. xs650

    xs650 Senior Member

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    +1. If anyone reports results much different than that it makes me think the problem was in the test. They are called the Laws of Thermodynamics instead of the suggestions of thermodynamics for good reasons.:D
     
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  9. uart

    uart Senior Member

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    However there is the possiblity that the ethanol makes the combustion slightly more complete or that cars with variable timing can make use of the slightly higher octane rating. So while 4% should be about the maximum hit you take with E10 I can still believe it possible that the figure could be lower (at least in some cars).

    I've previously seen figures between 2% and 4% quoted by very credible sources. Like I said my best efforts to measure it in the Prius usually give a figures of around 2.5% to 3% reduction.
     
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  10. richard schumacher

    richard schumacher shortbus driver

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    Ethanol cleans injectors and valves, and reduces pollution. Don't forget to price those benefits.
     
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  11. don_chuwish

    don_chuwish Well Seasoned Member

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    Whenever I can I fill up at a SeQuential Biofuels station, a small chain here. They of course have BioDiesel for the diesel crowd but also sell E10. Claiming to get all their ethanol from local Oregon sources.
    Sometimes after I fill up there I seem to get noticeably better FE than usual. My suspicion is that their blend isn't always the full 10%, maybe when supply is a problem. I don't really know, don't mind at all of course. Love to support the way they do business (read more on their site).

    - D
     
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  12. uart

    uart Senior Member

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    That's interesting Don. As I said I usually get quite a small reduction in MPG when filling with E10 but surprisingly one of my best tanks ever was one time when I filled about 1/3 E10 and 2/3 regular (making it equivalent to about E3) :D

    I don't know if that was a just a coincidence or something though.
     
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  13. F8L

    F8L Protecting Habitat & AG Lands

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    It may reduce emissions at your tailpipe but what about the emissions emitted during creation of ethenol? Please also consider the total energy lost when converting fossil fuel into ethenol.
     
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  14. qbee42

    qbee42 My other car is a boat

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    I prefer to drink my ethanol, after which I shouldn't drive, so mileage becomes a non-issue. Jayman would be proud of me.

    Tom
     
  15. Bob.H

    Bob.H Junior Member

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    Corn and ethanol are both subsidized by government making ethanol in gasoline a tax. Then its taxed again at the pump. Then we pay again with up to 4% loss of fuel economy. Us the consumer is getting nothing but we are paying big time. I noticed the contains ethanol sticker is missing from all of the pumps now. I am sure that is part of the way it is being hidden.

    In my opinion, we do need to test bio-fuel production methods. Maybe there will be a scientific breakthrough that makes it cost effective. Ethanol from fermentation of grain has been done for thousands of years and it's just not possible to magically make that economical as fuel.

    Bob
     
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  16. dbcassidy

    dbcassidy Toyota Hybrid Nation, 8 Million Strong

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    A very good and valid point. The sad thing about ethanol is the emissions created with the planting, fertilizing, growing (read water consumption), harvesting, transporting, distillation, transporting to facility to blend with gas.

    Seems to me more emissions are created generating a gallon of ethanol than a gallon of gas!!!

    Also, with ethanol, you have to constantly deal with the other problem few people seem to talk about. ethanols' ability to soak up water like crazy!!

    Ehanol can clean injectors, but ethanol can also damage (water content) injectors too.

    FWIW, I treat every tank of gas with either Startron or Seafoam additive to counter any ill effects of water ladened ethanol.

    So my question is, what have we gained by using ethanol?

    Dbcassidy
     
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  17. xs650

    xs650 Senior Member

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    People who are part of the corn lobby or their hired Congress Critters have gained a lot.:eek:
     
  18. bigcwill

    bigcwill Junior Member

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    Two local gas stations have put up huge banners that say "NO ETHANOL".

    I give them most of my business.
     
  19. dhancock

    dhancock 2 Prius Family

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    And let's not forget another (cost) factor: the resulting increase in the price of corn in the food market:rolleyes:
     
  20. qbee42

    qbee42 My other car is a boat

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    The cost of stove alcohol for my boat has more than doubled since they started adding it to gasoline.

    Tom