I had a 2007 GMC 1500 Classic 4WD with the 6.0 liter engine. Bought it new and traded it with 110K miles. Mine had the old 4-speed auto and about the best that I could do running empty was 17 mpg. Pulling my double axle flatbed with my Polaris Ranger on board, it dropped to 12-13 mpg. It looks like the 6.2 in the 1500 still uses the 4-speed auto.
We traded ours primarily because of the cost of feeding it. We put around 30K miles on each of two vehicles each year and the cost of fuel was unacceptable.
