FTC on MPG-decline vs. ethanol content
 

Some (short, 3 page) reading on FTC.GOV about decline in fuel economy vs. ethanol content:

http://www.ftc.gov/sites/default/fil...7105-00022.pdf

This is counter to what some forum members have been saying.

EDIT:

Plenty of other studies with way better data that disagree, don't feel like finding them again. U of Nebraska, U of a Dakota. I have 30,000+ miles that disagree as well.

Ive been mixing some e85 into my tank. I find some makes the mpg go down, more makes it go up. :eek: 6 gallon e85 vs 4 gallons e10 for a tank is a good mix. :thumbup:

That seems counterintuitive given the lower btu content of ethanol but I realize there are other variables inplay here... but even so...any idea why that works better than straight e10?:confused:

...because the refineries *use* the higher octane rating of ethanol when they "blend" lower-grade gasoline to make E10 = 87 octane.

So in pther words the octane kick from the ethanol combined with lower grade gasoline gives more overall btu content?

If E20 was 20% cheaper and gave 7.7% less MPG, I could live with that.

In a round-about way, yes, but the "...more overall BTU content..." comes more from the density of the lower octane gasoline feedstock, which they *blend* UP with enough ethanol (typically less than 10% as E10 label states) to achieve 87 octane rating...plus (or minus) the butane they add/subtract for winter/summer RVP control per EPA regulations.

There are scientific reasons but essentially it simplifies to a faster and thus hotter burn. The amount of ethanol reauired to see a gain is dependant on engine design and ecu programming just to name a couple.