(R) Recommended Practice for Measuring Fuel Economy and Emissions of Hybrid-Electric and Conventional Heavy-Duty Vehicles
|Publication Date:||1 May 2020|
This SAE Recommended Practice was established to provide an accurate, uniform, and reproducible procedure for simulating use of MD/HD conventional vehicles (CVs) 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.
Requirements Used to Develop the Recommended Practice
This document was developed to allow for the fair, representative, repeatable, and accurate testing of medium- and heavy-duty powertrains so that direct comparisons can be made between hybrid-electric and conventional powertrains.To meet this goal, the following guidelines have been followed:
a. This document will provide a recommended practice to measure CO2 emissions and fuel economy of any type of conventional and HEV design, including charge depleting and charge sustaining.
b. Where applicable, driver selectable modes may be evaluated (e.g., turning off regenerative braking).
c. The use of the existing powertrain test cycles provided with this document is highly recommended, but this document allows for the creation or adjustment of test cycles to better represent the powertrain's in-use application.
d. Testing shall not require defeating or otherwise forcing a powertrain's control system to perform differently from the way in which it would perform in use (potential exceptions include grade estimation algorithms that may affect dynamometer testing).