I just did two round-trips NY - Miami and averaged 15m/g in my 6.0l PSD, with a light boat trailer (about 1000#s) and cruise control set to 75. Consumption as per overhead console which might not be accurate. Heading back down to Clearwater in a couple of weeks and I'll do a calculated consumption average. But I love the truck; its a pleasure to drive on long distances which is what I bought it for.