Impact of worldwide test procedures on advanced technology fuel efficiency benefits

Abstract

In the context of reducing the dependence of transportation on fossil oil, a large number of alternative automobile technologies are considered, including a start-stop system, hybrid and plug-in hybrid vehicles, a full electric vehicle, and fuel cell. While some of these technologies have already been introduced into the market, others are still being developed. To meet future government regulations (i.e., Corporate Average Fuel Economy [CAFE] in the United States, carbon dioxide [CO2] in Europe..., vehicle energy consumption is critical. Different standard test procedures have been developed to evaluate vehicle performance. The U.S. Environmental Protection Agency (EPA) uses the two-cycle procedure based on the Urban Dynamometer Driving Schedule (UDDS) and the Highway Fuel Economy Test (HWFET); Europe uses the New European Driving Cycle (NEDC), and Japan uses the JC08. As vehicle energy consumption varies from cycle to cycle because of the different driving conditions represented, different powertrain technologies might be more or less effective at reducing fuel consumption. As a consequence, car companies might make different decisions regarding their technology of choice, based on where the technologies are sold. This study assesses the performance of various powertrain technologies in the different standard test cycles in terms of fuel and electrical consumption. The results are then related to car sales in different regions of the world, in an attempt to explain carmakers' choices regarding vehicle technology.