I've had a GMC 3.0 4WD for about 1-1/2 years now and 75K miles and love it. It's been leveled and has larger tires than OE tires and it get @ 21 mpg in my driving which is mostly on the road. The bigger tires and leveling really hurt the mileage by almost 6 mpg. I drive over 80 mph on the interstate. With a less heavy foot you will get better mileage as I get almost 25 mpg in roads where I stay around 65 mph.
Oil change and tire rotation every 7500 miles costs about $160 at the dealership. Change fuel filter about every 25k miles. 5 gallon DEF tank is good for 2500 miles.
Love this truck, but if I was mostly driving around town I would probably have a gas burner. That 6.2L V8 engine is a beast and will pass anything but a gas station.
