Hi, i often checked the MPG on my 57 Brum when “On Tour” to Scotland, Ireland, the IOM,and other long trips. The 600cc (coil ignition) engine and the (heavy )weight of the Late Shipley and the Brum will not return much more than 50 MPG, at 55/60 MPH. Blatting around on IOM Parade laps on the Brum ,reduced the MPG to 40/45 MPG! The Older the Scott the better they are on petrol,as the early bikes are a LOT LIGHTER. Regards Geoff.