Here in Texas, the land of the BIG SUV and trucks I have noticed when I pull in to fill up with my usual 10 gallons(I don't like to go below 3/4 tank) the SUVs owners are noticing my lack of time pumping. they some times ask how much does it hold or how far can you go? a few will notice the hybrid badge and ask what kind of gas mileage do I get, but most just watch as I'm in and out before they have gotten 1/2 of their fuel, and watch in envy.

 

Yeah, I notice that too.
After a few drive-up window attendants noticed my car was silent, and noticed it was a hybrid and started asking questions, I put stickers on the back "54 MPG city / 42 MPG hwy" which is what I get in mild weather.

I just came from Nebraska where I had to use 87 octane.
Now I'm back in Denver's mile-hi altitude and I refueled with 85 octane.
There was some beneficial fuel-trim settings from this switch.

Last night I drove 78 miles at ~ 65 MPH and net 46.7 MPG for that trip.

MPG drops when I step up the octane when I travel East.
However, the air density goes up as well. So there is more than one variable.
-John

 

I have been wondering this. When I was flying airplanes we would always try to get above 7000 ft msl to minimize fuel consumption but it also limited power. So a happy medium was 7000 to 8000 with 7000 just about perfect. At 7000 you would have a 30% reduction in power but the air was also 30% thinner so your speed would be good. You could run at full throttle and only load the engine to 70% power, which is max cruise power setting. The octane may be responsible for a little, but since this is an Atkinson cycle engine it can make use of lower octane fuel and actually get more power.