Several alternative vehicle and fuel options are under consideration to alleviate the triple threats of climate change, urban air pollution and foreign oil dependence caused by motor vehicles. This paper evaluates the primary transportation alternatives and determines which hold the greatest potential for averting societal threats. We developed a dynamic computer simulation model that compares the societal benefits of replacing conventional gasoline cars with vehicles that are partially electrified, including hybrid electric vehicles, plug-in hybrids fueled by gasoline, cellulosic ethanol and hydrogen, and all-electric vehicles powered exclusively by batteries or by hydrogen and fuel cells. These simulations compare the year-by-year societal benefits over a 100-year time horizon of each vehicle/fuel combination compared to conventional cars. We conclude that all-electric vehicles will be required in combination with hybrids, plug-in hybrids and biofuels to achieve an 80% reduction in greenhouse gas emissions below 1990 levels, while simultaneously cutting dependence on imported oil and eliminating nearly all controllable urban air pollution from the light duty vehicle fleet. Hybrids and plug-ins that continue to use an internal combustion engine will not be adequate by themselves to achieve our societal objectives, even if they are powered with biofuels. There are two primary options for all-electric vehicles: batteries or fuel cells. We show that for any vehicle range greater than 160 km (100 miles) fuel cells are superior to batteries in terms of mass, volume, cost, initial greenhouse gas reductions, refueling time, well-to-wheels energy efficiency using natural gas or biomass as the source and life cycle costs. (C) 2009 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.