Last month had a server go down after hours in our Washington, PA location. Normally I rent a car for trips to our Pitt and CT offices. So fueled up Bronco and jumped on turnpike in Morgantown, PA Ramp 298 right before I got off TP to interstate 70 (about 250 miles) I fueled up and did math I got right around 21.5 MPG (all turnpike, no traffic, cruise set at 70mph majority of trip) I have made several trips to Cape May NJ and have gotten anywhere from 19-20 mpg, but my daily commute for the week Is usually around 17 - 18 mpg..
All depends on the the way you drive, the traffic, and the road conditions.