You're right on par, my friend.
I've been averaging 17-18 MPG and I have 31k on my non-PPSHO. When I had my 2008 and 2009 BMW 335i, I would average 16-18 MPG. They BMW changed their platform to a single large Turbo instead of a TT, which increased their MPG.
I think this is the main push behind the 2016 using the 2.7 Ecoboost engine platform. The 3.5 TT is a hog from what I've experienced.