Consumer education and other market-oriented approaches to environmental protection require coherent information on the environmental performance of the products in question. Although light-duty vehicles are a focus of numerous federal and state policies, information on the environmental performance of vehicles is fragmented. Heightened interest in market-oriented approaches motivates the development of a more integrated approach to motor vehicle environmental information. An environmental rating methodology for light-duty vehicles was developed on the basis of principles of life-cycle assessment and environmental economics. The method was designed given the limitations of the available data by make and model in the U.S. market. It combines the impacts of traditionally regulated (criteria) pollutants with those of greenhouse gas emissions, covering both the vehicle life cycle and the fuel cycle, by using a mass-based characterization of vehicle manufacturing impacts. This methodology was applied in a consumer-oriented publication that was first released in early 1998 that will be updated annually. The data issues, assumptions, and analysis methods used to develop these vehicle ratings are addressed. The application of the methodology to model year 1998 is summarized. Finally, research needs for updating and refining the methodology are identified.