Hmmmm.... I doubt it! My question would be why would you want a 550 HP big block and be concerned with fuel economy? My mild 502 (with a 6-71blower) could average about 4 MPG.. if I took it easy on the loud pedal, and that was running $3.65 / gallon race gas. I have no idea what it will get after the rebuild is finished, but I can always add a larger fuel cell.