Purchased 5/5/06, current milage 2294, total 37.7 mpg.
Tonight I just got back from a 250 mile round trip and averaged 40.1mpg (computer showed 39.5). This is the same trip my wife took a few weeks back and averaged 36 mpg. Unfortunately her trip is in my totals or I would be over 38.
However she complained because I drove the speed limit and took longer than I used to. She'll get used to this. When she drove she drove 75 to 80 and did not let off the gas pedal on down grades to let the car "coast". She's getting the hang of it though.
I did run some numbers and found that the difference in 36mpg cruising (easy to do at higher speeds) and 38 mpg cruising (you have to drive with purpose for this) would only mean 1 gallon more used over a trip of around 700 miles. I haven't turned totally "green" yet, I'm just in this to save gas, so I probably will some day stop being obsessed with the ultimate number and go back to high speed 36 mpg cruising on trips and save the 39mpg tanks for around town and local driving when I'm not worried about cutting an hour or so off of my trip.
In the flats between Huntington and Charleston I was able to cruise on the interstate along with traffic and easily stay above 40 mpg, with the instant reading staying most of the time in the 50 to 60 range. However most of my trip today was in the long hills north of Charleston to Central WV on Interstate 79. I am very peased and confident now that I should NEVER see any thing less than 36. That's 20 better than my Infiniti.
I also make the trip to Mom's for $17, where as it was more like $40 with the premium fuel in my FX. That's gobb's better then the Ford Expedition (14.4) that we recently got rid of that was our "daily" driver.