Well, now that I’ve officially ran down a full tank rather than adding to it when I feel uncomfortable about the availability of E85 on a trip, I can write down some thoughts about it. First off, yes, I saw quite a mileage decrease over 93 octane fuel. This was to be expected. I’m estimating based on how I drove on that last tank that I might have seen around 25 mpg on gas, while I got just a hair over 21 mpg on E85. This equates to a slight savings in $$ over the premium fill. I’m hoping I’ll be able to nearly eliminate the difference once I get the wideband O2 sensor so I can adjust my timing after getting it at stoich.
As for the changes in the car’s personality? It’s much more responsive prior to the power enrich range when attempting to pass on the freeway. 65-80 in 3rd is practically instantaneous as far as one should be concerned. Cranking idle is a bit rough at first, but I’m fairly sure there’s something in the tune that I’m missing that will improve it. I’d estimate that there is a good additional 10% power under the entire curve over running 93. It’s quite significant.