DIESEL FUEL ECONOMY
QUESTION: I have a ’17 Ford F-350. The truck has 13,000 miles on it. I see 14.3 mpg in town at 6,200 feet elevation. On the highway in California, it gets 16 to 17 mpg. I hear reports of much more than that. Am I getting the mileage I should with a 6.7L Power Stroke engine? Is there any modification I can do to improve mileage? The numbers are for the truck empty with driver and one passenger. Thomas Goldenberg
ANSWER: We receive plenty of questions related to fuel economy on diesels because there’s not yet an EPA requirement to list mpg for heavy-duty (10,000-pounds-and-up GVWR) pickups. From our experience driving Fords and in doing comparison tests against GM and Ram pickups in the same segment, your mileage is on par with the expected fuel economy for that type of vehicle. All the newest ¾- and 1-ton trucks we’ve driven get between 18 and 19 mpg on the open road (at 60 to 65 mph), 14 to 15 mpg in combined driving, and 12 to 13 mpg in actual stop-and-go city traffic. We test pump to pump, filling up at the same fuel pump, topping off the tank, and then figuring actual mpg instead of using OBD II data. Remember, driving at speeds more than 60 mph has a negative effect on fuel economy. Aerodynamic drag increases with the square of velocity, and with pickups, the effect of drag really shows itself at speeds more than 60 mph. Fuel mileage can drop 10 percent driving 65 mph instead of 55 mph. Lift kits and taller tires also increase drag as well as add weight, which also affects fuel economy. In addition to drag, engine rpm contributes to fuel economy: Higher driving speed and engine rpm yield lower fuel economy. Easing into and out of the throttle will give the best mileage. There are a lot of variables. However, the zero-cost way to improve mpg numbers is to slow down on the highway and regulate the modulation of the right foot.