Ethanol blends

Decreases what? If your talking MPG, I have seen zero change with E-10.

Can't help you on your classic car.

Once again, you state a half-assed question. "Ethanol blended fuel decreases....." Decreases what? It's not even a complete sentence for heaven's sake. Yes, alcohol has less power and for the percentage used it decreades mileage by something like 25% I believe. Alcohol up to 10-15% is probably usable in most cars without a problem except for the reduced mileage. Carbureted vehicles may have a lean stumble and rough idle. Even at 15% alcohol, some vehicles before 75' or so may have problems with the alcohol affecting rubber gaskets and seals. About all you can do is take your chances and see what develops. PS. If it ain't a flex fuel vehicle, don't think about using E85.

Ethanol contains less energy than gasoline. So you get less fuel milage with ethanol than with gasoline.

Jeff

Ethanol reduces fuel mileage by 25% over gasoline at what percentage? Certainly not at 10-15%. The absolute WORST it could do would be to reduce it by 10-15% if the ethanol had NO energy content. IF ethanol has 75% of the energy density (BTU/gallon) it would produce 25% less mileage than gaoline - STRAIGHT. At 10%, that would be 2.5% reduction in output/mileage.

The question isn't as easy as some would think.

You can't just say "ethyl alcohol has 75% of the energy of gasoline therefore it will take you 75% of the miles that gas would". Measuring the chemical energy (as enthalpy) is a good first start, but you have to consider other factors like the temperature of the reaction, etc.

Someone made the comment that even if alcohol has zero energy and you blended it at a rate of 25% with gas, you would get 75% of the mileage of pure gas. That doesn't seem plausible to me. There are too many other factors. As an example, some of the energy created by combusting gas would be "wasted" heating and/or vaporizing the alcohol.

I can tell you that I've measured my MPG when I use E-85 versus E-10, and I get approximately 10% less MPG with E-85. My car gets around 22 MPG with E-10 and 20 with E-85. I statistically measured the difference and came up with 2.5 MPG less with E-85 with a 95% confidence interval of 0.5 MPG to 4.5 MPG.

I think the only way to know for sure is to measure your mileage in your car with and without alcohol (at whatever concentration you use).

John

This is a general statement that may or may NOT be true. It really does vary with the car. If you run E-85 in your FFV vehicle, chances are you will get less mpg. If you run 10% ethanol, you may get the same, less or maybe more mpg. Once again, it really does vary with the car and if your car needs the added octane that the 10% blend has, usually two octane points, at least in my area. I always end this with a story about a Chrysler K car that my parents had back in the late 80s-early 90s. I was living a good distance away from them at the time and they told me that the mpg with regular unleaded was about 22 or 23. With 10% ethanol they claimed to be getting in the upper 20s mpg with it. I didn't believe it until I put on about 500 miles with it and verified that it was true. In this case, I think the car had a lot of carbon in the combustion chambers and the added octane was greatly welcomed because of the increased compression. In a new car, maybe the miles per gallon would be worse, who knows? Currently in my area, 10% ethanol is $.10 a gallon higher than regular unleaded and the E-85 has been pulled because the cost got to be about $.30 cents a gallon higher than regular unleaded. FWIW, I live in the corn belt where farmers plant the majority of their crops to corn. With the probability of decreased gas mileage and a higher price, why buy it?

There is more energy in a gallon of gasoline than a gallon of ethanol.

A gallon of gasoline has 125,000 BTU of energy while a gallon of ethanol

84,400 BTU of energy. So ethanol has about 2/3 the energy of an equal volume of gasoline. So E85 has about 70% of the energy of gasoline and E10 has about 97% of the energy of a gallon of gasoline.

So you should get about 3% less milage with E10 than with gasoline.

High octane gasoline does not mean more energy. In fact, E10 has about 3% less energy than gasoline.

In real life, cars with ethanol in them do get less milage than with gasoline, because the same volume of ethanol has less energy than gasoline.

Jeff

Jeff

Flawed logic. I don't know the details of this specific matter but your analysis on caloric content alone is way over-simplified. The ethanol is mixed with the gasoline evenly, it's not like the injectors send in nine spurts of gas then one of ethanol. It is easy to believe that this might lead to only partial combustion. Or it might retard the burning rate so that unburned fuel is still in the cylinder when the exhaust valve opens. Or any of a dozen other possibilities.

There _IS_ a significant difference in the mileage I'm seeing from gas bought in different regulatory areas where the additives are different. I've seen a mileage difference from 34.560 to 28.524 under identical driving conditions, the lower figure being on "up to 15% ethanol" gasoline. That's 17.5%, and since the ethanol content is known to be at most 15%, clearly there is something more at work here than the relative energy content you could obtain from the two fuels in a bomb calorimeter.

As has been stated before, by others, it is imposible to predict the mileage difference with any accuracy, and also impossible to know what else is different between the ethanol plend and the nonblended fuel, chemically, as there is NO definition for gasoline motor fuel that restricts the refinery from re-formulating their gasoline to use whatever mongrel feedstocks they have available.

I have experienced SIGNIFICANT mileage difference from regular to mid premium on several vehicles, with the mid premium outperforming the regular (one example being a twin cam 95 neon - which has no knock sensor or adaptive timing control, to the best of my knowlege) It pings on regular.It gets better than 10% better mileage on gasoline with a high enough octane to stop the ping. Ethanol or not. I have also had experiences where a vehicle(1981 Tercel) got more than 25% better gas mileage when run on Amoco unleaded purchased in the states than I could ever get on any canadian fuel (back in 1983) Better mileage even on an American Gallon than I could get on the larger Canadian version.Ethanol was not involved in those years - but gasoline didn't smell the same then as it does now, and the Amoco smelled different than our Shell or Esso.

On my current (1994) Pontiac 3.8, I can squeeze 30mpg (canadian) out of fuel that says "may contain up to 10% ethanol" and have never bettered that mileage with any regular grade (or mid premium, for that matter)

I know my reasoning was not 100%, but I cannot believe adding 10% ethanol to otherwize identical fuel will reduce mileage, particularly on an electronically controlled engine, by anywhere close to 25%. My experience hasn't shown it, either.

Hi,

I have bin running my 00' Mitsubishi Carisma 1.8GDI (true direct injection) with 5% Ethanol unleaded for 5000 highway kilometers. They say that Ethanol mixed gas give poor milage and loss of hoursepower. But that is not my experience, i acturally get better throtle responce and same milage. And i think that it is good for my engine that Ethanol mix burns much cleaner the normal gas.

Best... Leon