Only a moron would use E85 in anything, let alone a fine machine like a 911.
I completely disagree, and it is ignorant to say so. Stock, no a 911 cannot use E85 fuel. It has a very different burn characteristic and energy output than normal gasoline. It requires larger injectors and more fuel to put out the same energy as gasoline, so fuel consumption would go up if one switched over to E85. The alcohol in E85 also keeps the engine cleaner (not just from an emissions standpoint but from a carbon buildup standpoint as well).
However, there has been a recent movement within automobile racing groups that do not have huge, virtually limitless budgets, to switch over to E85. Compared to normal gasoline, E85 costs more because of the amount of fuel needed to power the car. However, compared to race fuel, it is much cheaper and has some interesting benefits. E85 has a much greater cooling effect on intake charge compared to gasoline because of the alcohol content, and has a very high octane rating as well. GST is a small tuning shop racing a turbocharged Subaru Impreza with a 2.5L Boxer engine very successfully, and recently switched over to E85. Not only could they increase the PSI of the intake charge with the turbo because of the new fuel, they were able to advance ignition timing past the most effective point. Pretty good stuff eh?
However, unless you plan on racing the car, I don't think it would be worth it on a 911 unless you want to prove you can do it yourself. E85 is not widely available in the United States as of yet. You also have to change your fuel lines and many gaskets in the engine and fuel tank as alcohol is quite corrosive to many pieces compared to gasoline. I've been pondering building a 1970-1975 911 with a 3.2L swap and 100mm bore pistons to raise displacement to 3.5L, replace all body panels with carbon fiber/fiberglass, strip the car, weld in a roll cage, make the car as light as possible (theoretically I think you can get the car to weigh less than 1900 pounds if not lighter) and run a twin plug ignition on top of E85...you could run a very high theoretical compression ratio with that fuel and ignition set up, easily exceeding 350hp at the crank, if not much more. I would love to take that with a full race suspension and take on some time attack races =) It'd be one freakin fast car.