Some of these options include equipping trailers with aerodynamic features to reduce drag, low rolling-resistance tires, tire pressure monitoring systems, and weight reduction measures.

California Air Resources Board (CARB) is leading the nation in air pollution control efforts and has already begun a program that allows for aerodynamic device manufacturers to obtain a preliminary approval for the measured performance of aerodynamic drag reduction technologies, or combinations of technologies, in accordance with the provisions of 40 Code of Federal Regulations (CFR) § 1037.211. This program is called the Trailer Aero Device Approval Program. This program aims to align California's GHG emission standards and test procedures with the federal Phase 2 GHG emission standards and test procedures to provide nationwide consistency for engine and vehicle manufacturers. 

Under the Trailer Aero Device Approval Program, Computational Fluid Dynamics (CFD) is now one of the approved testing methods used to measure the drag area (CdA) of aero devices in addition to the traditional methods of coast down and wind-tunnel testing. Out of the three methods included in the program, CFD is by far the most cost effective and efficient method to use for CARB certification and allows flexibility in the number of iterations that can be explored before manufacturing a physical prototype.

Some examples of aero devices you may need to test include trailer skirts, trailer tails, tractor-trailer gap, the underbody of a trailer, or mudflaps. CFD may be a good fit for getting you where you need to be for preliminary approval for CARB certification before you end up scrambling to get there.