I get between 15 and 20mpg in town and 25 to 30mpg on the interstate.
20 is rare, but driving as light-footed as I can, it can be done. 15 is less rare. It only gets that low in almost pure stop and go stuff, which I rarely see.
On the last major interstate drive, (South Carolina to New York to Missouri to Kansas back to New York), we averaged about 28mpg overall. That was with me, my wife, and our 6 month old daughter plus all of our gear. That was keeping the cruise control (mostly) locked at 70mph.
Vehicle: 2005 Hyundai Santa Fe, 3.5L V6, 5 speed auto.