https://nacfe.org/research/technology/trailer-aerodynamics/vented-mud-flaps-trailer/

Vented Mud Flaps – Trailer

A variety of mud flap alternatives have been on the market for many years offering improved aerodynamic performance and fuel savings. The consensus is that these devices should be beneficial but the amount of fuel saved is hard to determine in individual tests.

Vented mud flaps are designed with holes or other means of allowing air to flow through while maintaining the function of lowering water spray and deflecting other objects. Many different designs are commercially available and adoption is growing significantly.

To learn more, download the Trailer Aerodynamics Confidence Report.