Definitely. Luckily they quit using it in Utah last year. The drop in MPG correlated almost mathmatically with the percentage of ethanol in the fuel. I'd see the usual drop of 2-4mpg when it daily got below freezing then an additional 10% (which coindendentally was the % of ethanol in the gasoline) when they began adding ethanol at the beginning of december. I've mostly seen this problem in newer engines. Old engines aren't so picky in my experience. My '77 Camaro showed no signs of decreased MPG's. Both my '93 and '99 Accords dropped when using fuel with ethanol.

 

Ethanol is used as an octane booster, most fuels have it in small quantities.

 

Gvs simply said his 205 tires are bigger than stock. Ralph told us the actual size, which is smaller in diameter. So, either way it makes a difference in one direction or the other...