Vortex Generators

Keeping the air flowing smoothly across the tractor-to-trailer started with cab extenders, sleeper extenders and most recently added sleeper top extenders to the cab.  Some drivers and fleets have used vortex generators on the back edge of the cab or extenders to further guide the air flow to the trailer.

 

There are several suppliers of these systems.  Some are installed individually while others come in longer strips to allow several to be installed simultaneously.

Benefits

The improvement in fuel economy is small enough as to be below the noise level in test data.  None of these systems is EPA Smartway certified as of August 2020 and they are not available as a factory installed option from tractor or trailer manufacturers yet.

Many drivers report that using these devices have keep their trailers cleaner due to the revised air flow.

Some of the products have a side benefit to make them more visible at night.  Some glow in the dark while others have reflective surfaces to reflect headlights.

Handling and steering become easier if there is no wind buffeting of the trailer.

Challenges

These systems add a tiny amount of weight to the vehicle

These generators do not cost much money, but they may not save much fuel either.

Decision-Making Tools

What Fleets Are Saying

“We continue to update our fleet with more fuel efficient post-2014 U.S. Environmental Protection Agency emission compliant engines, install aerodynamic devices on our tractors, and equip our trailers with trailer blades, which all lead to meaningful improvement in fuel efficiency.” — Knight Transportation

“Appearance and detail of our equipment means a lot to our drivers. Drive wheel fairings don’t just save us money, but our drivers like them too.” — Brad Pinchuk, Hirschbach

“Sleeper tractor aerodynamics have been finely tuned by all OEMs. Eliminating various features can add 10% to a fleet’s fuel expense,” — Chief engineer at a major truck builder.

Conclusions

  • Fleets should use the standard, optimized aerodynamic packages developed by tractor manufacturers and should not remove aerodynamic options that are included in the base model. Depending on the features removed, fleets will see as much as a 10% decrease in fuel efficiency.
  • Tractor and trailer heights should be matched for as many miles driven as possible as the fuel economy reduction from mismatched heights is in excess of 10%.
  • Fleets operating day cab tractors should pursue greater adoption of tractor aerodynamics than is common today, as many day cabs operate at highway speeds during nearly all of their duty cycle, where aerodynamics can offer as much as 13% gain fuel efficiency. Even day cabs operating in start-stop city driving will see savings from certain aerodynamic technologies.
  • Tractor manufacturers should design and make available aerodynamic features for day cab tractors as the industry migration to shorter hauls will likely result in more day cabs seeing significant highway and interstate miles.
  • Aerodynamics have not been fully developed for all day cab configurations, including natural gas, and the tractor manufacturers should develop and release these components.
  • Alternative fueled vehicles including battery electric and hybrid electric are subjected to the same aerodynamic forces as diesel-powered vehicles. Manufacturers need to keep that in mind as they design these alternative fueled vehicles so they are optimized for aerodynamics. In addition, manufacturers of add-on aerodynamic devices need to begin work on adapting their products so they can be used with alternative-fueled tractor.
  • Future EPA and NHTSA Greenhouse Gas regulations will challenge tractor builders to continue to improve the aerodynamic drag of these vehicles in excess of what has been demonstrated in the Department of Energy SuperTruck I and II programs. OEMs should start planning for this today, as the lead time required to design new models is significant and can be costly.

Manufacturers

AirTabs

Eco Fins

V-Spoilers

VorBlade