At 3200 miles, I've seen an improvement from 19+ a couple thou ago to 20.7 last time I filled up.

Mixed 2-lane highway & city (suburban), rolling hills, I use the cruise alot (I really think that helps), and have been known to wait on accelleration for a hundred yards so I can do it downhill.

But then again, Night Armor cars have a lower ballistic coefficient so you automatically get better mileage!