with a 5.3L V8,
and a full load of people and luggage, managed to hit:
and to average
For those of you who don’t understand L/100KM, that’s a “best” of 25.33MPG (Imperial) and an average of ~24.75MPG.
And this was on a 24h (OK, 25 1/2 one way, but that was on the way back when we took a route that was an hour and a half longer) trip Google said was 26h. I am quite content.