5.3 stroker with an F-1A-94 @ 25 psi gets around 12-13 mpg around town. I drove 5 hours up to Dallas last year for the LMR show and averaged 15.5 that trip.
A couple weeks ago I drove to a car show which was about 130 miles one way. Managed 13mpg going up and 16mpg coming back. I've since driven it around town and I think I'm between quarter and half right now at about 100 miles on the tank. But those have been some fun miles.