[Ryridesmotox]

I run an Ethanol/91 mix when I want to go fast. It is good for about another 40lbs.ft of torque over straight 91 the way I have my car tuned. I also run about 5psi more boost when I am on my Ethanol tune. It's good stuff if you can find it. There are a few pro/cons though...

Pros:
Able to run more timing in the tune
Able to run alot richer since Alcohol based fuels carry oxygen molecules in the carbon chain and petroleum based fuels don't.
It has a high detergent effect on valves because of its alcohol base so it runs quite clean.
It is very boost friendly since it is considerably more knock resistant than 91 octane.

Cons-
Hydrophilic (attracts water) and is therefore probably not the best choice if the vehicle will not be running for any length of time as water may start to infiltrate the fuel
The alcohol tends to crack rubber so anything that isn't a hardline steel fuel line may fail in the future
You will get HORRIBLE fuel economy on it. I get 30% less in my car and I run E85/91 in a 50/50 ratio.
Good luck finding an E85 station. There are 3 in San Diego county, luckily 2 are by my house.
You will undoubtedly go through tires and brakes quicker because of the extra power. lol

Honestly though the real advantage is in a forced induction motor. Mine (as an example) can run 5 more psi of boost AND 10 more degrees of timing at WOT (and thats at 50/50 ratio because my stock fuel system can't get enough E in the cylinders). Naturally aspirated engines will probably have more benefit from race gas.