You probably don't need any more comparison data, but here's mine anyway: I've got a stock 09 V, 1800 miles, MikeShields GT screen. I ride mostly back roads in western NJ at 40-60 mph, with occasional runs down I-78 at 65-85 mph. I don't know whether I get better mileage at higher speed on the interstate, but I'd guess not. On the backroads, I keep rpm in the 4000-6000 most of the time, in 4th or 5th gear. On the interstate, I'm in 6th gear running 6000-8000 (whatever it takes to keep up with traffic and not get run over by the trucks).
With all that, I get 50 mpg most of the time. As much as 51.4. Once 49.8.
I read once that best mileage from an engine viewpoint was at max torque rpm. If you're running much higher rpm than that, then mileage probably suffers.
Perhaps someone on the forum can give data on their mileage when running mostly at 80 mph or so.