This is a difficult question, as there are so many factors that affect gas mileage (transmission type, rear or 4 wheel drive, number of cylinders, etc.) that comparing isn't easy. In general rear wheel drives have much better mileage than 4 wheel drives. According to federal estimates for 2007, the Chevy Silverado gets the best mileage, in 2008 it was the Mazda B-Series, and in 2009 it was the Silverado again.
Right now the pickup truck that is getting the best gas mileage is the Chevy Silverado Hybrid. Because it is a hybrid, it uses technologies that help it burn less fuel.
The best gas mileage truck is the 2011 Ford F150's which get 23 MPG on the highway with the V6 engine.
Considering that a diesel pickup truck can't use gas I would say that there aren't any diesel trucks that get good gas mileage. If you were wondering which diesel truck gets the highest miles per gallon then I would say you should look at the Dodge Cummins diesel.
If you want gas mileage with power, and reliability, particularly with the transmission, Cheverlet is hard to beat.
A good 4x4 small truck with good gas mileage is a Chevy or ford pickup truck. Those have always been some of the small 4x4 trucks that have had good gas mileage.
The average gas mileage for the Mitsubishi L200 Warrior pickup truck is 34 mpg. Actual mileage will vary depending on the driving conditions and the mechanical condition of the vehicle.
25mpg
Top Gear USA - 2010 Better Gas Mileage Pickup Truck Alternatives 2-1 was released on: USA: 24 July 2011
http://fueleconomy.org shows a number of pickup trucks that offer the best gas mileage. One of the best being 2013 Chevrolet Silverado C15 2WD. The cost to drive 25 miles is $5.51 and the fuel required is 1.47 gallons.
It really depends on the engine. For that reason, the average gas mileage for the average pickup truck is anywhere from 13 to 20 miles a gallon. So, to attach a definite number on it, it's probably hitting around 15 or 16 miles to the gallon.
No one truck, no one answer. It will depend on the fuel mileage for the truck in question.
The best things to look for in a used truck, much less any used vehicle, is gas mileage and engine condition. Gas mileage is for gauging deterioration and checking engine condition is key or else you will buy a car while having to pay for the repairs as well.