I'm on my third tank, and I've been resetting my average at every fill-up. My average has been steadily improving with each tank. The first tank was about 15.5 and I'm at 17.7 on this tank so far. So it looks like it does get better as the engine breaks in. Also, I always try to keep my RPMs in the green zone on the tach (so no more than about 2,000 or so).
***I <3 my 2012 Liberty Jet!***