i get a lil over 20 mpg in my D150 /6 od833 truck, something my 84 chevy silverado 350 th350 could never do, lucky to get 12 mpg! 85 diplomat 318 904 got bout same as my /6, 76 charger with 360 and 727 bout 12 to 14 mpg, 79 roadrunner with E58 360 727 with factory high stall got 15 mpg if you stayed outta it! 71 cuda hot 318 with J heads 904 if drove easy got 16 to 18 mpg! 71 duster 340 X block bore 4.080 X heads LD340 intake holley 750 .508 cam hemi 833 with 3:91s turning N 50s got better smiles to the gallon than miles!!!