Photography by Evan Sears
Although no one is likely buying these heavy-hauling Kings of Beasts based purely on fuel economy, we know it is a real issue for every truck buyer.
We filled up our test trucks at least 10 times during our 1,600-mile journey from Dillon, Colo., to Las Vegas, past Flagstaff, Ariz., up to Moab, Utah, and finally back to Dillon. Our route led us to nine different fueling stations, many of which were populated by curious onlookers. It's not every day, apparently, that you see identically equipped bright orange brand-new flatbed trailers and two new, fully optioned 2013 one-ton pickups.
To provide accurate and informative fuel mileage numbers, we haven't included the two fill-ups after our Davis Dam acceleration and exhaust brake testing, as well as the fill-ups after the Eisenhower Pass acceleration and exhaust brake testing. As you would suspect, those runs produced much lower average mileage numbers due to the nature of the tests. Many runs were done repeatedly at wide-open throttle, certainly not ideal for fuel-economy data collection.
Over the 1,500 remaining miles that we logged on the trucks with their 24,000-plus-pound trailers, the Ram 3500 HD recorded 8.08 mpg while the Ford F-450 averaged 7.95 mpg. Statistically, this is a dead heat, as the two numbers are within one percentage point of each other. Historically, the Cummins has done poorly in tests versus both the Power Stroke and the Duramax turbo-diesels.
Neither truck's onboard trip computer's average mileage information was particularly accurate, with the Ford's being the most optimistic "guesstimator" of calculated fuel mileage. The Ram's computer seemed much more accurate, and it even shortchanged itself on one fill-up calculation. The Ford's computer, if you added up all the fill-up readouts and averaged them, calculated the Power Stroke average at 8.5 mpg (when actual mpg was 8.0), while the Ram's computer calculated the Cummins' average to be 8.2 mpg (our results showed 8.1 mpg).
On our full-length trip, the Ram recorded the best tank average at 10.3 mpg (its worst was 7.5 mpg); the Ford's best was 9.6 mpg (its worst was 7.0 mpg).