[Caddylackn]

The previous version of your Crown Vic is capable of close to 30 mpg stock. The 91-97 years were more aerodynamic and many had 2.73 rear gears. 28 mpg highway was typical of these when these were new. Of course these have the older non-PI head 4.6 motor that only had about 210 hp or so. Finding one of these older models and putting in your newer 2003 motor and a tune should get you in the upper 20s, maybe mid 30s mpg with some conservative driving, simple aeromods (grill and front undertray). The newest model crown vics have the worse aerodynamics (horrible rear window design), are heavier and have 3.55 rear ends typically.

These years crown vics share the same drivetrains as mustangs, and yes people do swap 5 speed manuals in them.

The city mileage of the older models is probably not much better than yours. Heavy car.