What is the fuel mileage on a Harley Sportster?

Fuel milage varies from bike to bike. My best answer is this comparison , MY 2007 Nightster with Vance and Hines exhaust and K and N air filter gets 52 MPG . My 1976 Sportster with _65A mufflers and S and S Super B gets 25 MPG. Age and modifications , riding style, air pressure, etc, Affects fuel milage . I hope this answer helps.