Comparison of dynamometer power absorption characteristics and vehicle road load measurements

The report presents vehicle road load force versus speed curves and Clayton dynamometer force versus speed curves. The vehicle road load force data were collected in the recent road load project, where the vehicle road load, as a function of speed, was determined for sixty-three light-duty vehicles. The dynamometer data were obtained from the six EPA certification dynamometers. This data is first used to generate an equation to represent an average emission dynamometer. The variations of the individual dynamometers about this average dynamometer curve are discussed. Subsequently, each vehicle curve is compared to this average dynamometer curve. Variations between different vehicles are discussed, and the possible intrinsic error caused by differences between the shape of the dynamometer force versus speed curve and the typical vehicle road load curve is investigated.