Closing in on a 10 mpg truck

The backbone of DTNA's 9.31 mpg big rig is its 2014 model Cascadia Evolution tractor, which the company says offers a 5% improvement in fuel economy over its 2013 model. Half of that gain comes from changes to its DD15 engine and the addition of the new DT12 automated transmission, with aerodynamic improvements responsible for the other half. One of those aerodynamic changes: no mirrors mounted on the tractor's hood.

A new side fairing design coupled with Lo-Pro tires helps reduce aerodynamic drag along the 2014 Cascadia Evolution tractor.

Wide base tires and wheel covers on the rear tandems of the 2014 Cascadia Evolution reduce weight and aerodynamic resistance simulataneously.

Longer cab fairing extenders and a special trailer nosecone cut drag created by the gap between the tractor and trailer -- without compromising manueuverability.

If the size and shape of these trailer side fairings look familiar, you're correct: they are the same as the ones used on the tractor.

Wide base tires and wheel covers on the trailer axles again reduces both weight and aerdynamic drag for the combined vehicle as a whole.

A DTNA-designed trailer tail completes the aerodynamic improvement package for the company's 9.31 mpg truck. Yet DTNA stressed that all this work doesn't mean it's getting into the trailer aerodynamic device business; rather, it's just an example of the lengths to which its engineers go to test out what's possible in terms of delivering greater fuel economy performance.