E85
Ethanol is a better solvent than gasoline, though. If you have the stock 17 year old fuel system, it's probably got some crud in it. Ethanol is a pretty good solvent, and will keep a fuel system pretty clean. It can break crud loose and it can clog up fuel injectors; kind of like atherosclerotic plaques causing a heart attack. A fuel filter close to the injectors wouldn't be a bad idea, and change it frequently for the first few thousand miles.
Many modern calculations have shown that fuel consumption between pump and E85 is 30+% when converting to E85. I believe a general rule of thumb is approx. 33% more fuel required for E85.
As noted E85 will "clean up/knock loose" any material build up in fuel components so make sure your fuel tank and components are flushed/cleaned before adding E85. I would also make sure the injectors and fuel pump are compatible which was posted by someone above. When I had my setup tuned for E85 I ran a Stainless Steel 10 Micron Fuel Filter then a secondary 100 Micron SS filter. Some people note that they have not had any issues with the paper type filters but I wanted to be sure as this was several years ago. I cleaned the filters every 6 months or so but again that might have been overkill.
I also used PTFE lines as PTFE is compatible with E85. PTFE lines are a pain to work with and more expensive then conventional fuel lines. Some people have used non-PTFE lines and been ok and others note that OEM fule lines have worked well.

