NASHVILLE -- Trailer aerodynamic devices work, but how well depends on the products and users’ operating conditions, says the latest Confidence Report from the North American Council for Freight Efficiency.

The report says fuel economy benefits of trailer aerodynamic devices range from 1% to over 10%, with high ranges claimed by manufacturers and low numbers cited by fleets, said Mike Roeth, NACFE’s executive director, during a briefing Sunday, prior to the opening of the Technology & Maintenance Council’s annual meeting.

Most fleets are choosing a combination of technologies to deal with reducing aerodynamic drag in one or more key areas: the tractor-to-trailer gap, the underbody, and the rear. The report deals with box-type van and reefer trailers, not other types, Roeth said.

Trailer aerodynamic devices reduce drag so it takes less fuel to move a vehicle down the road, especially at higher speeds. And while many aerodynamic devices for trailers have been around for years, cheap fuel has reduced dollar savings and stretched payback periods to as much as 24 months.

But fleets will have to make the investments in aero products because of the upcoming Phase 2 greenhouse gas emission standards, and the current regulations in California, Roeth noted.

This Confidence Report details devices for improving the aerodynamics of the gap, underbody, and the rear, as well as more novel options, such as vortex generators, wheel covers, and mud flaps.

The report describes each device’s unique challenges such as durability, deployment, trailer to tractor ratios limiting miles, a split incentive due to buyers of the aerodynamic devices not always buying the fuel, the ability to measure the fuel savings, and others. The study team found that trailer aerodynamic technologies and strategies are constantly and rapidly evolving.

The options detailed in the report are all currently available on the market today, and most are mature with a good track record of functionality, though they may be more or less economical depending on the specifics of a fleet’s operations. An executive summary and the full report are available at www.truckingefficiency.org.