I drive a mix of highway and city and get about 17.5. If I drove around here only, it would be much higher. I commute to work right now so cant tell you for sure what it would be. I have seen it at 20 on the DIC just around here. However, there are some long stretches to get to town.
I got around 17.5 with city only when I lived in Dallas. In Utah, with mainly highway miles I get 18.5-20. I'm more than satisfied with this as all my JK's and 4 Runner's got under 15.