The Effect of Standard Ambient Conditions on the Determination of Vehicle Road Load and Fuel Economy

A new set of standard conditions for the road coastdown procedure was established from the literature. The change in road load predicted from the road and dynamometer coastdown procedures was evaluated using this new set of conditions and the current set of conditions for a twenty four vehicle sample. These changes in road load were related to changes in fuel economy using relationships published by the Environmental Protection Agency. No significant change in fuel economy was predicted when using the new conditions. A sensitivity analysis was performed on the new set of conditions with respect to road load.