One of the best ways to save a lot of fuel is to improve the efficiency of the lowest-mileage vehicles on the roads.
Those include semis, which often get no more than 2 or 3 miles per gallon of diesel fuel.
Their huge diesel engines must put out massive torque to tow one, two, or even three trailers, and the resulting assembly has some of the worst aerodynamic drag of anything on the road.
Since 2008, an entrepreurial startup called ATDynamics has been selling its $2,000 "Trailer Tail," which mounts on the rearmost trailer to smooth the airflow coming off the back, reducing drag and improving fuel efficiency.
Founder Andrew Smith says that the tractor's fuel economy can rise by 6 percent, meaning that the Trailer Tail can pay back its cost in reduced fuel expenses in less than two years (depending on annual road miles covered).
The company scored its first big sale last year, to a New Mexico trucking company that ordered 3,500 Tails. Three more large trucking firms are now evaluating the product, and the company is also working with truck maker Navistar on an efficiency program to improve truck efficiency sponsored by the U.S. Department of Energy.
ATDynamics is hardly the only maker of aerodynamic aids, and it faces an interesting customer challenge: Many tractor drivers haul trailers owned by other entities. The trailer owners have no incentive to cut fuel usage, so the Tail may be best suited to companies that own and operate both tractors and trailers together.
Still, with Federal fuel efficiency standards for heavy trucks rising substantially in coming years, you can expect to see more efforts to move more trailers around on much less fuel.