here is a pic of my MPG readout... I am on cruise control doing 65mph on the 5 fwy in Northern California near Stockton (so it's pretty level country) and I am up to 20.0mpg. To show this, I attained the 65mph speed, waited a bit, then reset the trip computer to get an average reading only at this 65mph speed.
Not bad for a 300hp V8, I say.