Actually with those numbers and me in my 3:91 geared, torqueflite shifted 3-speed... thats gas sipper territory I believe my mileage was in the 11 range and worst open highway trying to keep up with 75-80 mph. Maybe 9 But the sound of that 340 small block at 4800 rpm in sswwweeeettt. The sight of that next gas station is a pain in the.... wallet