Okay, I am going to plan on 15 to 16 mpg on Interstate 5, around town 13. My 1972 F250 with a 460 and a Holly carb gets 10 mpg, I am hoping for better than that. BTW, the truck is the only vehicle I have driven where you can really watch the gas gauge go down. I should have left the original 360 in it, who needs all that power in an old 3/4 ton truck?