LOUISVILLE, Ky. — As diesel fuel costs escalate, North American fleets continue to expand their use of "tails" on trailers to improve aerodynamics and save fuel.

In announcing the expansion of its TrailerTail program in the U.S. ATDynamics, says the add-ons are gaining in popularity as fleets struggle to offset the rising prices at pumps.

ATDynamics announced that it will significantly expand its TrailerTail product line during 2011 to meet growing demand.

One new product to be launched in the fall of 2011 is the TrailerTail Nano, a reduced-length model delivering an expected 4 percent in fuel savings.

Nano is a compact aerodynamic alternative aimed at fleets with length constraints, namely Canadian carriers dealing with specific regulatory requirements, as well as inner-city operations, and pup-trailer fleets.

The product is clearly in part aimed at a Canadian market said to be ready to embrace such devices, but constrained by regulatory barriers.

Werner Enterprises is the most recent fleet to install TrailerTails on 130 dedicated trailers, ATDynamics reported at the Mid America Trucking Show in Louisville.

The company says standard TrailerTail delivers 6.6 percent fuel savings at 65 mph.

"Diesel prices are well above $3.00 per gallon and the average trucking company spends over 5 percent of their fuel budget overcoming aerodynamic drag at the rear of their trailers," said Andrew Smith, founder and CEO of ATDynamics. "Fleets utilizing TrailerTail technology operate more profitably and more sustainably."

Mesilla Valley Transportation, a top 100 U.S. fleet based in Las Cruces, N.M, currently operates the largest fleet of TrailerTail in the industry.

The trucking company launched a 15-month program with ATDynamics to retrofit its entire fleet of 3,500 trailers.