Ethanol decreases my fuel economy by 3 mpg along with a big drop in power which is especially noticable while pulling my trailer.
the reason for this is because ethanol contains less energy per gallon than regular gas. therefore, a gallon of gas cut with ethanol will have less power than a gallon of straight gas. this is all fine and dandy, if ethanol was comparatively cheaper than gas (like how gas is comparatively cheaper than diesel)... but its not. around here gas that has been cut with ethanol sells for the same price as straight gas, so there is absolutely no advantage to using it (or having the govt subsidize it).
here are the stats:
Liquid hydrogen has 33,696 btu/gal
Ethanol has 84,600 btu/gal
E85 (85% ethanol and 15% gasoline) has 90,660 btu/gal
Liquefied natural gas has 90,800 btu/gal
Gasohol (10% ethanol and 90% gasoline) has 121,000 btu/gal
Regular gasoline has 125,000 btu/gal
bio diesel has 126,200 btu/gal
Jet fuel, naphtha has 127,500 btu/gal
diesel has 138,700 btu/gal
for those of you who dont know, btu means British thermal units. so, skipping the technical explanation, basically higher numbers mean more energy per gallon.
edit: Corn is the main feedstock used for producing ethanol fuel in the United States. the american method of corn production is extremely fertilizer intensive. the amount of ammonium nitrate used in traditional american corn production is exponential. industrial production of ammonium nitrate uses power primarily derived from coal plants. the required electricity for many ethanol distilleries also comes mainly from coal plants. there has been considerable debate about how sustainable / renewable corn-based bio-ethanol really is.