Words by Mike Levine, Mark Williams and Kent Sundling, Photos by Ian Merritt
Our final test of the three heavyweights was fuel economy, because every time you have to stop to refuel, you lose time and money.
We measured fuel consumption over almost 2,000 miles of travel with the trailers behind the trucks the entire time. The results exclude segments where we were testing the trucks, such as on the mountain climbs and at Chrysler’s proving grounds. As we’ve seen in earlier tests, the Ford F-350 had the best fuel economy while towing, at 9.5 mpg. The GMC was close behind at 9.1 mpg, or a difference of $22 over 2,000 miles. The Ram had the worst mileage, at 8.5 mpg, costing $115 more to operate than the Ford.
Ford’s and GMC’s DEF systems – used to scrub nitrogen oxide emissions to meet federal regulations – allow the engines to operate more efficiently with less exhaust gas recirculation than the Ram. While DEF runs about $2.99 a gallon and the Ford and GMC have DEF tanks that hold about 8 gallons, it’s well worth the cost. We started out with full DEF levels in both trucks and never had to refill during the trip, and no low-DEF warnings came on.
Our past measurements show DEF consumption at about 2 percent of diesel fuel, though it might have been higher because of the heavy loads and high stress we were putting on the trucks.