I pump the tires up to 40..get better mileage. My dealer recommends minimum 87 octane. Stations here in the midwest sell a lot of gas mixed with 10% ethanol.
The price is a few cents less per gallon and sports a higher octane. I get less mpg with the ethanol blend which I think is typical. I guess its a choice of better mpg with straight gas or a vote for less dependence on oil with ethanol blend.
Also, I tried Mobil 1 which carries a $20 premium per oil change. I noticed no difference in mileage. I'm back to regular oil.
Mileage: 45 city about the same on the highway.
Take care