I get 19 mpg driving it to work in the city. I get 25 mph driving 80 mph on the highway. I get 10-15 mpg driving spiritedly on public roads. I got 5-10 mpg driving it 6 laps at COTA.
I happen to know all of these numbers because I habitually keep track of my gas consumption. I just don't care what they are
Also, premium only. If you're considering not putting premium in the Z, don't consider buying one.