I do use my own blends of Hydrated Ethanol (HE) HE70 to HE90's for more than a decade > I can mix any amount since the ethanol nozzle are at one foot from the regular gas, so... < My 1995 Taurus is US imported > gasoline only, original compression chamber values. It ran a lot with all the original parts and loves it! < The mileage drops about 15% at highway. City driving makes the gap wider (20% more to the thirsty side) than the highway driving. The combustion chamber (can't photo up with boroscopes) is clean and no excess carbon abrasives for the compression rings to eat up. I use K&N air filter (on original air box). It's doing 39mpg at highway cruising at 75mph. Mine came from factory with green fuel injectors, its original FFV injectors for export. Fuel pump went by last year (maybe the excess of hydrated ethanol has a hint of guilty in here) and I replaced with a 4 bar Delphy FFV, so the high amount of hydrated ethanol wont hurt a thing and the regulator makes it back to 3 bar. PCM is original gas only version though, not the FFV version. Last spark plugs are one grade hotter than the original ones.
The thing burnt about 425 gallon of pure water in its life, from the hydrated ethanol I added to the fuel mix (since in average, 8% of the ethanol I add is pure water). Ethanol fuel here is about the 92-94GL version FYI. That vapor makes my O2 sensor and catalist converter clean as a whistle, too.
Did the same in a 95 Golf GLX 2.0 8v and the Scooby. The Scooby still has the original Fuel Pump. The Subaru thing is Tough! Ethanol is about 65% the price of regular gas, so a higher consumpton still compensates.