my 08 f350 diesel was getting a combined town/highway of about 13mpg. i normally drive at a normal speed and our terrain is hills. driving 70 miles every weekend to our cabin in mass i started playing around. normal driving around 75 mph i was getting my usual 13mpg's. so, i slowed it down to 64mph and my mpg's jumped to 19.3 on the way home driving all hypermilager, about half highway and half town miles. the next week on the way up (a bit more up hill) i babied it again 65mph and got 17.2mpg. i think the sweet spot is at 1800 rpms. currious what cummins and d-max are getting. please specify terrain(hilly, mts, flat??) and driving type (hypermilager, normal, speeding) i hear the 2010 fords will have an inhouse built diesel without the burn chamber in the exaughst. maybe ill have to trade it in.