By Brian Wong, Cars.com
We put our four mpg contenders through a mileage drive in and around the Houston area. Each of the trucks ran a 120-mile loop twice: once without payload and once with 1,500 pounds of rock salt in the bed.
Our drive route was flat with little elevation change, and traffic was light for the most part, which helped each contender quite a bit. The majority of the drive loop was spent on open highways, and although there were sections of street driving, our calculated numbers skewed heavily toward EPA-estimated highway fuel-economy figures. We ran the second loop with each truck going in the opposite direction of the first loop, using the same roads and highways to avoid Houston's morning and evening rush-hour congestion.
Here are the results for the empty loop:
How They Ran Empty
The 2016 Ram 1500 EcoDiesel, not surprisingly, won both loops by a good margin, turning in numbers better than 30 mpg (better than its EPA highway figures) when empty and loaded. We did have some fuel-filler issues on our empty loop with the Ram due to diesel foaming with the capless filler hose, which can be a problem even if you literally see fuel going up to the cap. That forced us to rely on trip-computer mpg numbers for the Ram for our data. Calculations for the other trucks were done the normal way: We divided the number of miles driven by the measured gallons of fuel. We should note that we reset the trip computer for the Chevy and Ford at our first fillup; base Tundras like our tester do not have trip computers. (Editor's note: We'll revisit this fuel-economy issue at a later date and will retest the Ram EcoDiesel as soon as we're able.)
In terms of ownership costs, Ford recommends premium for the 2015 F-150's EcoBoost engine (although all the factory performance and EPA fuel-economy numbers were calculated with regular unleaded fuel), while the 2016 Chevrolet Silverado and 2016 Toyota Tundra use regular unleaded. The Ram, of course, runs on diesel.
Given that all our pickups were driven at or near the same speeds and in the same way, we weren't surprised the Ram outperformed the other larger V-8 gas engines by more than 25 to 30 percent. What did surprise us was how well the Chevy V-8 did with its new eight-speed transmission, offering better fuel-economy numbers than the F-150's V-6 and the Tundra's smaller V-8 (both those trucks are a good deal lighter than the Chevy as well).
And here are the results for our loaded loop:
How They Ran Loaded
This is where things get interesting. As noted earlier, our test loops in the Houston area were quite flat, so we knew from past experience that our loaded fuel-economy calculations weren't likely to be too much different from our empty numbers. But we weren't prepared for three of the four trucks delivering better fuel economy while loaded than their respective empty loops.
The Toyota, which had the smallest calculated payload capacity and was maxed out with our 1,500 pounds of rock salt and adult male driver, predictably experienced more than a 15 percent drop in fuel economy. However, each of the other trucks interestingly got slightly better mpg numbers with the extra weight. So the big question is why. We think the primary issue involved here, after talking with our test drivers, is that they tended to drive the pickups a little differently with full payload capacity. They were just a little smoother when accelerating and braking to give themselves a larger safety margin.
Additionally, since the Chevy Silverado has a smart, aggressive cylinder-deactivation feature in the engine (which came on just as often loaded as it did when empty), eight speeds to choose from and a rear end that actually had a lower aerodynamic stance on the road, it's probably not surprising that it did better when loaded either. And the Silverado had a bed cover over the rock salt load, which improved aerodynamics. In some ways, the same holds true for the Ford, although we deactivated the engine's stop-start feature to keep things apples-to-apples. We assume many of those same issues also relate to the Ram, the heaviest of our competitors.
How We Tested
Our four drivers rotated at three different points on the drive route so that each person drove each truck one time on each loop. All four trucks stayed together as much as possible, adhering to all posted speed limits. When filling our test trucks, we used the same fuel station, the same pump and the same double-click-filling method. Each truck was filled at the beginning and end of the loop.
All the pickups were driven with all the windows up, the air conditioning turned on and transmissions in Drive. Cruise control, Eco modes and stop-start were not used at any point during the trip.
Cars.com photos by Evan Sears and Angela Conners