My 2000 IH4700 (195HP) gets about 8 MPG, and it's almost always pulling the chipper. My 2006 F550 gets 8-9, and it has the dump trailer/Dingo behind 90% of the time. My new RAM 2500 gets about 16 normal, 13 when towing either of the above. Both tow options weigh ~7200 as is. Everything runs diesel.