As dave stated Alchol has much less energy than gasoline. In an engine designed to operate purely on alchol you can develop significant horsepower but none of the E85 caars are designed that way. Ther is much more to it than a little chippin.
Next, although E85 is not going to give you as many ponies in your new car it is far from a waste. Yes you do use more of it, and yes it costs more to operate the same number of miles. That is not the issue, it burns cleaner thus reducing emissions and it is renewable and does not come from the middle east. It is for this reason that I actually support the idea of increasing the taxes on gasoline. Until you can save money doing it most Americans will refuse to do the responsible thing when it comes to renewable resources and cleaning up.
As far as global warming, yes it is real, did man cause it? NO! If man was the cause of global warming then we have been roaming the planet since the last ice age. Think about someting, if we were'nt there to end the last ice age what did end it? Global warming, and we had NOTHING to do with it! Are we accelerating global warming? Probably, but IF you could get every one in every country to reduce their quality of life to the stone age you still could not stop global warming. The only thing that is going to stop global warming is when the planet reaches a critical temperature and the ice caps melt to a certain point and a certain ammount of land is under water and a number of other certain specification that scientists haven't got a clue about are reached the the planet will enter a Global Cooling phase and we will enter another ice age. How many of you doom sayers that feel me MUST STOP mans contribution to global warming have car? A furnace in your house? Use a lawn mower (gas powered)? Take warm showers? Use lights in your house? Any car made since the mid 80's creates 10 to 100 times less emissions than pre 1980's cars. That information alone says that we did MOST of the damage 30 years ago.
Think about what you are really willing to give up and do the math on what you will be doing to help and what you will still be doing to hurt and see where you really are.