318 mpg

I got 13 mpg w/ a fairly stock 340 4 speed 69 dart swinger w/ 3:23 gears on the highway 55-65. Had a couple darts with 318's that would get 18-22 with stock 2bbl and 2:94 and 2:47 gears. The mileage is there, you just got to get it right.