MPG with gas-ethanol blend vs pure gasoline

Discussion in 'General Motoring' started by Mister Bear, Nov 21, 2007.

  1. Mister Bear

    Mister Bear Guest

    Has anyone checked gas mileage (MPG) in the identical vehicle using an
    ethanol blended gasoline in one fill-up, and then pure (non-ethanol) gas
    in other fill-ups? All the gas pumps in my state have an ethanol
    blend, so I don't have a chance to compare with pure gasoline. I've had
    people tell me that pure gas delivers measurably better MPG ... better
    by 10% or more. Has anyone checked one gas against the other in the
    same car? Results?
    Mister Bear, Nov 21, 2007
  2. Mister Bear

    Roy Starrin Guest

    In a word, no. But the debate/discussion has lots of inputs.
    Simply Google: ethanol mpg
    Roy Starrin, Nov 22, 2007
  3. Mister Bear

    Jeff Guest

    Ethanol has about 30% less energy in it than the same volume of
    gasoline. So 10% ethanol gasoline should have about 3% less energy than
    regular gasoline. And you should get about 3% less gas mileage.

    Jeff, Nov 22, 2007
  4. Mister Bear

    Tegger Guest

    Esso in the province of Ontario started using ethanol last summer. Prior to
    that they used MTBE, which is also an oxygenate. Before that it was MMT,
    which is not an oxygenate.

    With my very detailed recored keeping, I noticed a couple of percentage
    point decrease in mileage when they switched from MMT to MTBE, but no
    change going from MTBE to ethanol.
    Tegger, Nov 22, 2007
  5. Mister Bear


    Gas has a higher btu rating than ethanol. You will get better milage out
    of 100% gas.
    Ive never really bothered to check the difference. When I had a 35-40mpg
    vehicle driving 15-20000 mile a year gas was cheap ($.80) so didnt care.
    Now I dont drive much 5000miles on a bouht new 2005Pilot. If two
    stations side by side one blended, one 100% I would go with the
    non-ethenol blend 100% gas.
    QUAKEnSHAKE, Nov 23, 2007
  6. Mister Bear

    Tegger Guest

    (QUAKEnSHAKE) wrote in

    No fuel is "100% gas". A goodly proportion is made up of detergents and
    other additives. Then you have the octane boosters.

    In the old days you had tetra-ethyl lead added as an octane booster. Later
    it was replaced by MMT. Neither of these had a significant impact on fuel

    What *did* finally adversely affect mileage was the addition of oxygen to
    the fuel. Oxygen was added through the use of MTBE or ethanol, the
    resulting fuel mix being known as "reformulated gasoline".

    If you want to maximize fuel economy, you have to remove the oxygen by
    going back to non oxygen-containing additives. Which ain't gonna happen.

    I did, and it isn't much. Perhaps 2%. Until you do whole-year studies with
    the same car, the same fuel brand and the same octane rating, it's
    impossible to pick out changes that are not due to simple randomness.

    You can find ethanol-free gas almost everywhere. It's usually in the form
    of the the "premium" octane grades, like 91 pump octane. The lower the
    octane, the higher the ethanol content. But you won't find non-oxygenated
    anywhere in North America now that MMT is out of use.
    Tegger, Nov 23, 2007
  7. Mister Bear

    John Horner Guest

    You have that one backwards Tegger. Ethanol has a naturally high octane
    variously reported at somewhere from 113 to 129 and is used in fuels
    in part to increase the final octane rating.

    In many cases premium fuels actually have a higher ethanol content than
    their regular fuel counterparts because adding ethanol is one of the
    simple ways to increase octane ratings.

    John Horner, Nov 24, 2007
  8. Mister Bear

    Tegger Guest

    I filled up today at a local Shell.

    On the pump was a sticker. It said:
    "87 octane: contains up to 10% ethanol
    89 octane: contains up to 5% ethanol
    91 octane: contains no ethanol."

    Want me to take a picture and post it?
    Tegger, Nov 24, 2007
  9. Mister Bear

    Jeff Guest

    The difference in energy content between E10 (10% ethanol) and E0 (no
    ethanol) gasoline is about 3%. At about $3.00 per gallon, that works out
    to $0.09. Not enough to make using higher octane worthwhile.

    Jeff, Nov 24, 2007
  10. Mister Bear

    John Horner Guest

    Post whatever you like, but the fact is that ethanol is a higher octane
    fuel than standard "gasoline" and is commonly used as an octane booster.
    I have no idea where you live or what the situation is with your Shell

    Have a look at the reference articles I posted or the dozens more which
    are readily available.
    John Horner, Nov 24, 2007
  11. Mister Bear

    Tegger Guest

    But ethanol is not used as a fuel in road cars, only as an additive in
    gasoline fuel. The Manitoba document you cite explicitly says you could
    not practically use ethanol as a fuel in road-going cars.

    Ethanol may be a high-octane additive, but it's a particularly poor
    choice as a gasoline octane booster. Ethanol was a non-starter (ha ha)
    before the government started hiding its real cost by taking money from
    your left pocket so they could put it in your right, and then by
    mandating the use of ethanol.

    Ontario, Canada.

    All the Shells in my province have that sticker, from what I've seen.

    The Esso stations in my province all have stickers that say the gas "may
    contain up to 10% ethanol". But then I checked the MSDS's for Esso's
    unleaded gasoline. No ethanol at all, just MTBE (up to 15%).

    Those pump stickers may be a legal labeling requirement rather than a
    reflection of what's actually in the gas.

    Shell's MSDS's do not even list the octane booster. They say only that
    gasoline makes up ">90%" of the fuel mix. Shell is probably taking
    advantage of the "proprietary" exemption from revealing its oxygenate in
    the MSDS's.

    I just did. The Manitoba government article is your typical
    ethanol-loony propaganda bumpf. Manitoba farmers are reaping a
    substantial financial harvest from the ethanol mandates, at the expense
    of taxpayers across the country.

    However, that article did contain this nugget:
    "In order to produce Regular Unleaded gasoline with ethanol, a blender
    must have access to an 84.5 octane (or "sub-octane") grade of petro-gas.
    In some markets sub octane gasoline is not made available to blenders.
    In these locations, Regular Unleaded (the lowest price grade gasoline
    with the highest sales volume) does not contain ethanol. In markets
    where sub octane gasoline is available, however, ethanol blended Regular
    is usually less costly than petro-gas Regular."

    I think the answer here may be that in my area they may be using sub-
    octane to make Regular. Then they're relying on the heavy tax subsidies
    that accompany ethanol to be able to offer heavily ethanolized Regular.

    Grades above Regular may use better base stocks which do not require so
    much ethanol to make them usable, but then the seller can't claim those
    subsidies, so has to charge more.

    And if our 91-octane uses MTBE instead of ethanol, there are no
    subsidies at all.
    Tegger, Nov 24, 2007
  12. Mister Bear


    An examble
    2008 Chrysler Sebring mileage ratings
    19/27 with gas
    14/20 with E85 (85% ethanol)
    This site shows
    QUAKEnSHAKE, Nov 26, 2007
  13. Mister Bear


    Explain E85. Is using 85% Ethanol still considered an additive?
    QUAKEnSHAKE, Nov 26, 2007
  14. Mister Bear

    Tegger Guest

    (QUAKEnSHAKE) wrote in

    I forgot about that. In that case the alcohol *is* being used as a fuel.
    Tegger, Nov 26, 2007
  15. Check out the flex fuel vehicles:

    notice how they are almost all trucks? The reason is that they get a
    big credit on their CAFE when they sell a flex-fuel vehicle. So,
    while you may think that your GMC Yukon only gets 15 mpg, GM gets a
    credit for building a 33 mpg truck. No shit. Of course few of these
    trucks will ever see E85. But the phony fuel economy rating allows GM
    to sell more Suburbans, Hummers and Yukons. In this very real way,
    E85 is helping to squander fuel and trash the environment.
    Gordon McGrew, Nov 27, 2007
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