I'm in Australia, I have a 2009 Toyota Corolla hatchback (toyota auris in Japan and Europe). is 1.8 L petrol engine (2ZR-FE) auto. same engine as most corollas in the States.
my consumption is 40+ on highway (+cruise control), around town is 37 to 39. I use 98 octane fuel.
I replaced the spark plugs for racing spark plugs, you can feel the difference in the response of the car when you accelerate.
and changed the airfilter. initially I had a high flow but the oil coming from it blocks your oxygen sensor, so I changed for the Toyota Aurion filter.
And by the way the best petrol I tried is the ethanol E85 (105 octane). but you have to adjust the ECU to get the best of it.
Have fun!!!