Have yet to do much driving in the 'new to me' 2007 Tour Master 40C, but last fall got around 9 MPG and was maintaining about 65 - 70 most of the time during a 600 mile round trip.
Expressed in ton-miles -- like they do for freight trains, that comes to about 135 ton-miles per gallon. Your typical compact sedan would need to get about 90 MPG to move that much weight per gallon of fuel...
Chuck