87 with 10% ethanol is the gasoline I have been giving a price for. 87 sans the ethanol is about .30 more per gallon.
We used to have 87 sans E, 89 with 10% E and 90-92 with or without E. A few years ago, they said the 89 10E was too expensive to mix 87 + 10% E, so they went to 85 base and added 10% to bring it up to 87. 89, 90 and 92 octane went away, now we have 91 and it varies from station to station is it is pure gas or 10% E.
In CA we have 87 (up to 10% ethanol),89,91 (or maybe 92?). Don't know if we have any other octanes in BFE locations. Those are what I normally see off the highways, etc. I know there are E85 stations around, but I don't think that many. I remember back at work the enviros always wanted to use E85 but there were never any stations near the office.
In Idaho a lot of pumps have four gasoline grades: 85,87,89,91 (or maybe 92, I can never remember the top in these parts).
I used to use 85 in the Trooper when on road trips and it ran fine. I haven't tried it in the 4Runner, and the new truck with the turbos has an 87 minimum.
But back to my original point, depending on the octane and composition of the regional "regular", I reckon that's going to affect a lot of our comparisons here.