If I may chime in. I pull the "3rd Day" with an 08 Chevy 2500HD Z71 Crew Cab, 6.0 gas and a 6 speed auto. Empty around town, 12.5, hwy 15-16. Trips to my local landing, about 5 miles ea. way and I've made the trip to the Lower Keys twice, 750 miles ea. way, and averaged 10 mpg@ 65 mph. This was...