If one is using it in place of a car, how about the little 4 cyl turbo engine Chevy offers? A year ago our local Chevy dealer loaned me a pickup while mine was in for service (their policy, great dealer!!). I didn't ask questions about the loaner. Just jumped in & drove home. I thought it was one of the low end V6 offerings. But, coming away from a couple stop signs I thought to myself, "I think this truck has more "go" than my 5.3 Silverado"! So, when I got home I popped the hood. It looked like an engine compartment from the '60s. You could see ground most everywhere around the engine. It was NOT a V6, but a little turbo I-4! I suspect 30 mpg+ would be the result of this combo. I don't know about towing, but I will say that I think in the 1/4 mile, it would beat my 5.3, which I don't think is any slouch.

If one uses a pickup as a car, maybe consider the turbo 4?