Two aerodynamic devices from Aerodynamic Trailer Systems will deliver a significant improvement in fuel efficiency when installed together on 53-ft van trailers, the company says. It says verified testing -- at the Continental Uvalde proving grounds per SAE J1321 standards -- confirmed that the ATS SmartTail side extenders and the WindTamer undercarriage fairing offer a combined fuel efficiency improvement of 5.3%  at speeds of 63 mph. And that's more than good enough to have achieved a key approval. The EPA’s SmartWay program confirms that the ATS combinations will satisfy stringent California Air Resources Board (CARB) legislation requiring 53-ft trailers operating there to have aerodynamic devices installed that yield 5% or greater verified fuel savings.

ATS adds that its boat-tail device used in combination with a trailer sideskirt actually yielded a nearly 9% fuel efficiency improvement at 62 mph.

The SmartTail, which is claimed to offer a 4.45% fuel efficiency boost at highway speeds on its own, is actually an inflatable device that is blown up automatically at a programmable road speed. It requires no driver action, immediately deflating if the trailer is moving in reverse or when it slows. Once deflated, trailer doors can be opened freely. It's said to weigh less than 125 lb in total. The polymer-skin inflation system eliminates moving mechanical parts that would be exposed to the elements and it's claimed to be maintenance-free. ATS claims that it also improves the vehicle's handling qualities and extends tire life by reducing "shimmy".

The WindTamer is not a skirt, rather a wedge-shaped cover mounted on the undercarriage of the trailer and directing air flow under and away from the aerodynamic mess of axle, suspension, and brake components. Its mid-carriage location mitigates exposure to road and wheel debris, says ATS, and prevents the build-up of snow and ice while providing more than 20 in. of road clearance. It's made of a lightweight and rugged polyethylene widely used for automotive rock shielding

Both products have a claimed 10-year life expectancy.