I have a 2014 6.2L with the 3.73 rear end (Max Tow) and I've averaged 12.7 L/100 km (18.5 US MPG) over the lifetime of the vehicle. A lot of that is highway driving but some of that is towing also, with winter fuel a lot of the year. I never put 87 or 89 in it, and overall quite happy with the vehicle. I highly recommend the 6.2L engine, it was the main reason I swapped from a 2500 since I didn't want a diesel.