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Several studies, conducted from 1997 to 2001, have employed vehicle and powertrain simulation models to estimate fuel economy gains for a variety of fuel-cell powertrains. Many of those studies have attempted to control for the comparability of performance between conventional and fuel-cell vehicles (FCVs), but different sets of performance goals and simulation models have been used. This paper reviews the estimates of fuel economy gain (in mpg) vs. varying measures of performance change for a set of those studies. We examine some of the potential causes for the variability of these estimates - fuel used, powertrain hybridization, vehicle raw energy requirements (load), and variations in analysts' assumptions/estimates - when substituting several types of fuel-cell powertrains. Our study includes development of a database and detailed examination of the relationships among powertrain and vehicle characteristics and fuel economy gain estimates for the selected studies.

Although many of the studies that use vehicle simulation models to estimate fuel economy gains for a range of hybrid vehicles have attempted to control for the comparability of performance between conventional and hybrid vehicles, different rules and simulation models have been used. This paper reviews the estimates of city, highway, and corporate average fuel economy gain vs. varying measures of performance change for a set of those studies. We examine the causes for the wide range in estimates when hybridizing a vehicle, establish a database, and provide detailed discussions of relationships using several of the studies. Statistical models developed on the basis of the data reveal the causes of variation in mpg gain among conventional/hybrid pairs that have the same 0-60 mph acceleration times. Our study reveals that potential mpg gain via hybridization is greater as the 0-60 mph acceleration time of the pair of compared vehicles drops (and power-to-weight ratios increase).

A two-stage Delphi study was conducted to collect expert opinion concerning long-term (2000-2020) technical and economic attributes of electric (EV) and hybrid-electric (HEV) vehicles in comparison to conventional gasoline vehicles. The study questionnaire was divided into three parts: the first addressed vehicles; the second, vehicle components; and the third, the impact on the transportation system of electric and hybrid vehicle use. This paper reports selected results from the first round of the survey. This international survey obtained information from 191 expert respondents in the automotive-technology field. The experts' skills predominantly reflected specialization in electric drivetrain vehicles and/or components.