They may not be the most numerous vehicles on the road, but heavy-duty trucks cover far more miles than the average car--and account for roughly 20 percent of overall carbon emissions from transportation.
The Obama Administration has taken steps to address this with stricter fuel-efficiency standards, most recently with proposed standards covering 2021 through 2027 model-year vehicles.
Rules already in place call for a 20-percent reduction in fuel consumption, and the proposed rules would require further cuts if enacted.
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But cleaning up their act might not be that hard, according to a recent report from Wired.
Trucks only account for 4.3 percent of traffic on U.S. roads, but they cover 9.3 percent of vehicle-miles traveled, according to the Brookings Institution.
Heavy-duty truck fuel consumption (courtesy of the Brookings Institution)
They also consume about a quarter of all fuel used by road vehicles--almost entirely diesel--and represent 22 percent of transportation emissions.
Given the huge expense of fuel, truck buyers and manufacturers may be more receptive to the idea of improved fuel economy because it has a greater immediate economic impact than it does for a car-owning household.
And unlike car buyers, heavy-truck buyers all use their vehicles for essentially the same purpose, so they can be courted as a group.
And since truck customers use their vehicles to make money, the potential savings inherent in lower fuel consumption will likely prove attractive.
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Because of that, many manufacturers are already working to improve fuel economy. Some reportedly claim to be exceeding today's Federal standards for fuel efficiency across their product line.
Further improvements could come from some fairly straightforward solutions, foremost among them aerodynamic improvements to reduce energy-eating drag.
Carmakers focus heavily on aerodynamics, but it hasn't been fully exploited in commercial trucks.
Walmart WAVE concept truck.
Concept vehicles like Walmart's WAVE and Daimler's recent SuperTruck show what a more radical shift in design could produce.
Closing the gap between the tractor and trailer, and replacing side-view mirrors with less-obtrusive cameras have also been suggested.
Low-rolling resistance tires and regenerative braking--two features any Toyota Prius driver will be familiar with--could also find their way onto big rigs.
Once this low-hanging fruit is picked, though, things could get a bit more challenging.
The industry doesn't believe battery-electric or hydrogen fuel-cell powertrains are feasible yet, owing to concerns about cost and range.
Still, given the mileage they cover every year and the amount of fuel they currently consume, even less-radical methods of improving truck fuel economy should produce worthwhile results.