I have the GMC sierra with 5.3. (06). I like it alot. Back seat on the ext cab has plenty of room, no one complains sitting back there. I really like the "tow mode" selector in the transmission. Push the tow selector on the gear shift and the shift pattern changes in the automatic transmission. Instead of shifting up at 1500 rpm it will shift up at 2000 to 2500 rpm (depending on torque). It will tow 6000 with no problem. Towed boat from Lake Michigan and travel time, gas milage was not noticably different than when I have made this trip without the boat. Please note that my boat is aluminum and weighs about 3500 lbs. So I do have much more truck than boat. The farm trailer with tractor on it is a different story. It will pull it without hesitation, but I have not pulled it more than 20 miles so I really cannot tell ya how that 6000 lb trailer affects milage.