10% Ethanol isn't a problem.
http://en.wikipedia.org/wiki/Flexible-fuel_vehicle

 

They have started using the Ethanol down here. I think its 10%. High test works' great on the long trips. Better mileage and great power.

 

I answered 90, but I hardly ever see 90.

I have the 2.4, so I always run at least 89... haven't noticed a performance or mileage increase with higher octane.

 

I use ethenol here at home and have good power and milege. Coming back from Ariz. I used 89 or 90 midgrade and was getting 31.5 mpg.

 

..and what is involved in this 'tune'?

 

Reprogramming the ECM.

 

all the pumps in the metroplex pretty much say ethanol

 

Although, Wikipedia is a good source to answer this question a much better one is your owners manual....starting on page 5-5 through 5-7.

A study conducted by GM about 10 years ago, indicated that almost 60% of the questions asked in the dealer service area, was answered in the owners manual of the respective vehicle.

I participated in that study/survey.

 

Custom tuning.. to the ECM..
air/fuel mixture adjusted (usually performed when exhaust/air intake is done) , shift preference, speed limiter open up,
rev limit up a tab bit more, firmer shift, Octane adjusted, rev limiter lifted out of gear...

 

I used 87 to start but now I use 93 because there is a station that sells it for 16 cents over Regular compared to the 20-24 cents over at other stations. As far as performance it does seem to run a little better and I noticed a 2-2 1/2 MPG increase over Regular --- before the road construction came, now I sit in 3-6 miles of stop and go traffic nearly every afternoon and I am still getting about 1/2 MPG better.