The newer vehicles aren't so bad, but some older engines and especially small motors like boats, lawnmowers and stuff are said to have problems with the ethanol causing problems with the fuel lines and seals as they aren't compatible. There is also some new emissions from burning the ethanol fuel that isn't in regular fuel. I think it's about 10% less if I remember right and if they get the E85 stuff going it could be worse. So depending on prices, you could be paying more for ethanol fuel to get worse mileage. The regular gas won't hurt anything either. There is more energy per gallon of regular gas vs the ethanol mix hence the lower mileage from the ethanol stuff. I ran it here until they quit offering it a couple of months ago and I did see better mileage.