Crown Vic/Grand Marquis gas mileage?

Narrowed my search to an Impala or a CV/GM. I owned a 1990 Grand Marquis Wagon that got about 26mpg on the highway, but I don't remember what I got in the city (odometer and trip-meter both broke). But I am looking into a 2002-2004 Crown Vic or Mercury equivalent, and have read they STILL get good gas mileage on the highway (25+ on flat highways at 65+mph). I am assuming around 18mpg in a hilly area around town, but I was wondering what you Ford/Mercury Detroit Dino owners have been getting around town and on the highway.