Very impressed with gas mileage

The 1976 Feather Duster and Dart Sport Lite with /6 and 833OD were the first American cars to be rated at 31 mpg hwy. Not the Vega or Pinto. /6 Mopars!
I got 17 mpg city over about 4000 miles in my 1987 D150 SWB /6 833OD 3.91
I just put a 2.93 SG in my 72 Satellite 440/727 and drove 230 miles at 70 mph average on 14 gal= 16.43 mpg.