Ironically, my 1999 K2500 with a 7.4 L V8 gets around 12 MPG pulling a loaded double axle enclosed cargo trailer down the highway (but maybe 13 MPG empty) and doesn't shift down 2 or 3 times to climb a hill.

It has been replaced by a 2018 K1500 with a 5.3 L V8 because it gets 20 MPG city/hwy and up to 26 MPG on the highway plus I just didn't need a 3/4 truck.

I will probably make my payments though...

Andy