MY 78 bird with a 305 gets 18 MPG @ 80 MPH. But that number was generated a few years ago. Since then I have changed the rear from 2.56 to 2.41 and put many miles on the motor. Would be intresting to run the numbers again, but not too intrested in going back to Nevada to run out two tanks of gas @ 80MPH. However, it was the absolute NICEST cop I have ever had give me a ticket. Nice, guy, really.