Sounds like something for the Mythbusters.

On Dec 28, 2012, at 5:25 PM, Marc Perdue wrote:

> Kim,
>
> Ethanol is added as an oxygenator to reduce knocking and pinging. As I said earlier, of course you won't get better mileage with a gallon of E85  vs. a gallon of 100% gasoline; gasoline has more BTUs per given volume. What I'm saying is that if you ADD ethanol to a gallon of gasoline, you've still got the same number of BTUs in the gas PLUS the BTUs of the added ethanol. The per unit mileage will go down, but the total shouldn't.
>
> Marc
>
>
> On Fri, Dec 28, 2012 at 5:18 PM, Kim Brennan <kimbrennan@mac.com> wrote:
> Sure it does. You're diluting how much power is available in each gallon, by putting alcohol in.
>
> They do this for EMISSIONS, not better fuel economy.
>
> On Dec 28, 2012, at 5:04 PM, Marc Perdue wrote:
>
> > Mike,
> >
> > I guess I misunderstood. I thought you were saying the number of miles per
> > gallon of pure gasoline vs. a gallon of e85 . . . It doesn't make sense
> > that adding ethanol would REDUCE the number of miles you could drive with a
> > gallon of gas...
> >
> > Scratches head...
> > Marc
> >
> >
> > On Fri, Dec 28, 2012 at 3:58 PM, Mike Riley <mkriley@fuse.net> wrote:
> >
> >> mark,
> >> I was the one that talked about the mileage not mpg. To make it simple I
> >> was talking about miles travelled. Take a given amount of pure gas and
> >> drive until  it runs out and read the miles travelled.
> >> Ad 15% ethanol to the same volume of pure gas and you will travel fewer
> >> miles on a greater volume of fuel!
> >> mike
> >>
>
>