This SAE Recommended Practice was established to provide an accurate, uniform and reproducible procedure for simulating use of MD/HD conventional vehicles and hybrid-electric vehicles (HEVs), as well as plug-in hybrid-electric vehicles (PHEVs) and battery electric vehicles (BEVs) on powertrain dynamometers for the purpose of measuring emissions and fuel economy. This document does not specify which emissions constituents to measure (e.g., HC, CO, NOx, PM, CO2), as that decision will depend on the objectives of the tester. While the main focus of this procedure is for calculating fuel and energy consumption, it is anticipated that emissions may also be recorded during execution of this procedure. It should be noted that most MD/HD powertrains addressed in this document would be powered by engines that are certified separately for emissions. The engine certification procedure appears in the Code of Federal Regulations, Title 40-§86 and §1065.
Code of Federal Regulations defines powertrain testing in 40CFR1037.550 as one of the methodologies to establish the fuel consumption maps for a powertrain (§1036.510) over pre-determined duty cycles and vehicle configurations. This technique allows manufacturers to capture the fuel economy benefits realized by optimizing the powertrain as a system, as these gains might not be completely captured when using an engine-only certification approach combined with the EPA’s GEM model.