Tapered devices -- boat tails -- fitted on the rear of trucks can reduce fuel consumption by as much as 7.5 percent, scientists in the Netherlands said.

Researchers at Delft University of Technology experimented with varying lengths of boat tails for a year to determine which was most fuel efficient.

Working first with small models in wind tunnel experiments and computer simulations, the researchers then spent a year testing varying lengths of boat tails on trucks on public highways, the university said in a release Friday.

A boat tail about 6-feet long improved aerodynamics enough to reduce fuel consumption by as much as 7.5 percent, while also reducing the amount of carbon dioxide released into the air.

The studies were supported by road transport manufacturers, transport companies and shippers looking to reduce fuel consumption by as much as 20 percent by 2020, the researchers said.