Rating the Environmental Impacts of Motor Vehicles: The Green Guide to Cars and Trucks Methodology

Public information and consumer education are important components of an overall strategy to address the environmental impacts of motor vehicles. Accessible information that rates car and light truck environmental performance can enable consumers to account for the environment in their purchase decisions, can help guide fleet programs and other market-creation initiatives, and assist automakers' efforts to market "greener" products.

To address these informational needs, since 1998 ACEEE has published the Green Guide to Cars and Trucks, an annual, consumer-oriented booklet providing model-specific environmental information for the U.S. automotive market. In the United States, the only known antecedent is The Green Buyer's Car Book (Dyson et al. 1994), which was quite comprehensive regarding impacts covered, but technical in style and was published only once. A number of other green, consumer-oriented car books emphasize driving and maintenance behavior rather than vehicle choice, although some discuss fuel economy ratings (e.g., Sikorsky 1991; Makower 1992).

In Europe, Verkehrsclub Deutschland (VCD, "German Traffic Club") and companion organizations in other countries have published environmental ratings for a number of years. (e.g., VCD 1997). VCD cosponsored a seminar on vehicle rating and the resulting report is probably the most comprehensive discussion of car rating issues to date (T&E/VCD 1996). VCD's rating system was updated in 1997 to provide greater emphasis to CO2 emissions; their approach also covers other use-phase impacts (including noise), manufacturing impacts, and recycled content, using a system that adds or subtracts points based on various vehicle attributes. The club has proposed a Europe-wide effort to develop uniform reporting requirements according to the principles of life-cycle assessment.

This report covers the data issues, key assumptions, and analysis methods used to develop the ratings used in ACEEE's Green Guide to Cars and Trucks: Model Year 1999. It summarizes the application of the methodology to the 1999 model year, highlighting results for major classes and technology types, and identifies research needs for updating and refining the methodology.