I like our C-12 a lot but mileage in the 10+ range occurs quite seldom...think more like 8.5 as a consistent average over time. You will love the effortless cruising at 1300 rpm and the Jake brake is like throwing out an anchor. The tranny is probably the 4060 Allison and our gear ratio is 3.43:1.
FYI, there is a function in the Silverleaf that show the avg MPG since the engine was born...have the owner pull that screen and there will be not boubt. By the way, the Silverleaf is a great device and I've found it to be very accurate. Put that on your must-have list.
