My 351W has 10.2 to 1 compression ratio and a little over 400 HP at crank. On a 600 mile trip of mostly highway driving, I got 22 MPG. That's with a 3:73 rear end gears and a 0.68 fifth gear ratio.
Of course, around town, the mileage can be anywhere from 12 to 16 MPG depending on the weight of my right foot.
