It is possible, I got 24mpg with my truck...once.
The fam and I took a day trip to Cleveland, 700 miles round trip, averaged 21 mpg for the whole trip.
I did the same trip a month earlier and got 24mpg on the way there, 20 on the way back.
Thats with just me and a suitcase, cruise at 65 and a/c on.
So it is possible.

 

Was it downhill both ways

I think the best I got was 19mpg driving to and from NYC. What was the sticker mileage on these trucks?

 

At the time, my D1 had about 120kmi

Eric

 

I just drove to Chicago yesterday and averaged about 19 mpg. Not too bad for the 'ole girl. I'm driving to Alabama tomorrow, i'll let ya'll know what comes outta those tanks

Edit: A/C Was not on, cruise was inactive due to Chicago traffic.