I worked with a guy who had been a Ford dealer line mechanic in the early-mid 80s. He swore a customer had a 351w powered 80-something F-truck which got over 30 mpg, when warranty work was done once there was a Ford rep there, & he heard about the truck getting absurd mileage. He said it was an experimental carb, so they installed a new one & destroyed the original, customer went to getting 10 mpg like everyone else. Guy still swears its true. Brian