We Hate To Ask But...How About Fuel Efficiency?

In 1973, the feds estimated that semis got about 5.6 miles per gallon of diesel, and today’s estimates are still abysmal. Going up a steep hill, a truck's mileage might drop to about 2.9 mpg, while going down the same hill will raise it to more than 23 mpg. This year Shell’s Starship concept truck used advanced aerodynamics and hybrid motors to attain… 8.9 mpg. (That said, it was carrying a heavy load and achieved 178.4 ton-miles per gallon, more than double the national average in the measure that takes payload into account.)

How do you make a huge, heavy truck more fuel-efficient? Fairings that hide the leading edge of the trailer, side skirts that prevent wind turbulence under the trailer, and round caps over the rear trailer doors all combine to improve fuel mileage. “Super single" wide wheels that replace dual wheels are said to improve fuel mileage by up to 7 percent. Trucks are also beginning to incorporate more composite materials—the same kind of transformation that in aeronautics produced the current set of super-efficient airliners, like the Boeing Dreamliner.