I just saw this thread. I don't feel like reading all the way through it, but my mother is an engineer for GM, so I have a little insight on the subject;
I asked her about it in my own self interest probably a year ago. She said that it is perfectly fine for a car and will not harm it in anyway as long as it is approved for the vehicle. As for cost, she said if E85 is one dollar less than regular, it is more economical to buy E85. Any less than a dollar and the lesser efficiency of the E85 will burn more than it will save. I have bought and used both and see no real difference. I buy whatever is supposed to be cheaper.
I asked her about it in my own self interest probably a year ago. She said that it is perfectly fine for a car and will not harm it in anyway as long as it is approved for the vehicle. As for cost, she said if E85 is one dollar less than regular, it is more economical to buy E85. Any less than a dollar and the lesser efficiency of the E85 will burn more than it will save. I have bought and used both and see no real difference. I buy whatever is supposed to be cheaper.