Truck and Bus Coastdown Procedure J2978_202106

DOI: https://doi.org/10.4271/J2978_202106

Issuing Committee: Truck and Bus Aerodynamics and Fuel Economy Committee

Publisher: SAE International

Rationale: Coastdown testing of trucks and buses has become common practice over the past decade as a means to quantify the magnitude of the road-load forces exerted on a production vehicle or to quantify the difference in road load forces between vehicles or vehicle configurations. Environmental regulations and energy-savings verification programs have adopted the coastdown method for evaluating the aerodynamic-drag performance of vehicles and the drag reduction associated with aerodynamic technologies. Using industry-accepted best practices, this SAE Recommended Practice establishes a procedure for the coastdown testing of trucks and buses weighing more than 10000 pounds.