Hannover, Germany. Having optimized the aerodynamics of its new European flagship Actros tractor, Daimler Trucks has turned its attention to the trailer and will begin selling add-on trailer devices developed as part of a new design study.

“Truck and trailer—they go together like screw and screwdriver, wheel and tire, pen and paper—there is no point to one without the other,” said Georg Weiber, head of engineering for Daimler Trucks.

Speaking at a press conference during the IAA 2012 Commercial Vehicle Show, he introduced an aerodynamic tractor-trailer combination developed with body builder Schmitz Cargobull that tests show cuts drag by 18% and fuel consumption by 4.5%.

The Actros tractor, a new model introduced last year, needed no new modifications, using standard side and roof fairings. The trailer was a standard European dimension refrigerated unit. Modifications included an air dam around the sides and top of the reefer, and full side fairings that are drawn in a bit at the front and lead to a scoop or air diffuser at the rear. The underbody was also treated with a full length diffuser. At the back, side and roof trim panels extend 400 mm beyond the rear door. The rear underguard also received an aerodynamic smoothing that includes flush mounted tail lights.

The price target for the full aero package is 6,000 Euros, which would provide a 2-yr. ROI based on increased fuel economy, according to Weiberg. Although the prototype is a bit heavier, the company expects to bring the package weight under 300 kgs, he added.

“We have no need for any futuristic dolphins on wheels, or pseudo-aerodynamic shapes with long hoods far removed from the realms of possibility,” Weiberg said. Instead the project combination is ready for the road with one exception—the boat tail panels take the vehicle past current European overall length limits.

However the Euopean Union Commission is recommending a 500 mm exemption to those limits for aerodynamic devices, according to Weiberg. “This is not a semitrailer for the distant future, but a semitrailer for 2013,” he said.

With the design project deemed a success, Daimler has decided to begin offering the boat tail, underbody diffuser and side panels through its Mercedes Benz Trailer Axle Systems subsidiary, Weiberg said. No date for production or availability was announced.