Too many variables.
Transmission.
Type of driving.
Air pressure in tires.
Driver.
Location.
Fuel matters.
Here is my fuelly
http://www.fuelly.com/driver/swarbrz
I gave up after a few tanks of e85 as the website uses current fill up to calculate costs, and previous fuel to calculate mpg, which throws some metrics off.
I was right around 28mpg 90% highway at 80mph on 91octane manual transmission.