Believe it or not, I can get 30 mpg highway in my Mustang...did it on a 5 hour trip with the cruise set at 70 the whole way.
I'm not sure about city though...I'd imagine it's probably low 20s, if not lower.
I haven't filled up in about 4 weeks though, since I'm able to walk everywhere on campus or take the bus, so gas prices aren't hurting me yet--that is, until winter rolls around and I have to drive an hour to go boarding!