2002 Chevy 2500HD crew cab, long bed, 4x4 6.6L Duramax diesel, 6 speed manual tranny, 3.73 differential probably 7000-7500 lbs empty around 21+mpg average since I bought it last July. Recent tanks are over 22. Of the 3 trucks I've owned, this is by far the biggest (others were reg cab), most capable (others were half ton, gas, 2wd), and MOST FUEL EFFICIENT (never broke 20mpg in others). I shopped around for months before deciding what to go with, and more months to find the one I wanted. I'm thrilled with the truck so far, and the tips here have so far given me at least an extra 1-2 mpg. I'm hesitant to do anything too out of the ordinary (like FAS) out of engine durability concerns, but some of the basics like keeping rpms low, DWB, and coasting in neutral seem to really help. Nevermind why I chose a truck in the first place and not something smaller. I have my reasons, but that novel can wait for another day. YEAH diesel!!! I with there were more oil burners to choose from in the US.