My first tank in the 07 SE roadster with auto trans, 26 mpg, on what I assume was premium filled by the salesman, but who knows?
I think he must have pumped it full as it took a while clear the full mark, and my filling didn't take so long to start going down. I'm just over 500 miles now odo and I'll see what I get when next purchase.
Most driving is country paved two lanes, state highways here in Michigan, and paved secondaries, at 50 mph since we've had snow most days and didn't seem prudent to floorboard her.
I see diminishing gas mileage in the spring.