E-85 is highly corrosive to fuel systems that are not made specifically for E-85. Most vehicles can tolerate up to about 10%-11% ethynol blended into gasoline without any harm. Vehicles designed to run on E-85 will have a yellow or green gas cap signifying that the it is safe to use E-85.
E-85 typically reduces fuel mileage by about 20%-25%, so you will have to do the math to calculated if your true fuel milage is offset by the lower cost. Also, many people report reduced performance with E-85, but then they were probably not looking for performance if they are trying to save money on fuel. My Mercedes requires 93 octane gas, but it will accept E-85 however my dealer advised against using it since performance would be severely compromised. There would be an obvious savings from premium gas to E-85, however I have never tried using E-85. There are not that many gas stations around here that sell E-85, so there is a big inconvenience factor in my using E-85, but I think I may give it a try just out of curiosity.
I personally am not a big supporter of using corn (food products) to make fuel. The increased use of corn to make ethynol fuels has already increased the cost of meat since corn is used in a lot of livestock feeds. It has been shown that Switch-Grass yields far more fuel per acre than corn, is not a food source, grows everywhere in the USA even in poor soil without adding expensive fertilzers, grows fast and can produce 2-3 crops a year.
The only reason farmers have not switched to growing Switch-Grass for fuel is that they are more familiar with growing corn and already have the equipment to plant and harvest corn.
Perhaps a government tax break incentive might convice farmers to start growing Switch-Grass for fuel on some portion of their land.
...Rich