I liked phill's crown vic so much, that i ended up buying my own. it's a 2001 police interceptor.
first tank of fuel i got 17.3 mpg, my 2nd tank of fuel i got 20.3 mpg.....did a lot fewer burnouts on the 2nd tank of fuel, also inflated my tires to just over max rated pressure. the mpg numbers are not quite up to par with what i expect from the diesel civic.
i did just change my oil to mobil 1, so we'll see if the 3rd tankfull gets me any better mileage. If i get ambitious i'll try to change out the oil in the rear diff with synthetic to see if that also helps to make a difference.