This study examines options for reducing emissions from motor vehicles and evaluates each of the options in terms of its public health, climate change, and cost implications, including the uncertainty associated with each option. We examine battery-electric vehiicles, fuel cell vehicles, the use of ethnaol blends in flex-fuel vehicles, and reductions in vehicle miles traveled. We find that increasing the use of battery-electric vehicles provides the greatest public health benefit per unit of GHG emission reduction, followed closely by the use of fuel cell vehicles, and then by reductions in vehicle miles traveled. However, all of these options involve tradeoffs and non ranks favorably along all dimensions. For example, batter-electric and fuel cell vehicles provide significant public health and climate change benefits, but both options involve high cost and uncertainty. Flex fuel vehicles consuming fuel blends containing ethanol derived from corn, on the other hand, have fairly low technological uncertainty, but do not provide any significant public health or climate change benefit.