There has been a recent trend toward the use of lifecycle analysis (LCA) as a decision-making tool for the automotive industry. However, the different practitioners' methods and assumptions vary widely, as do the interpretations put on the results. The lack of uniformity has been addressed by such groups as the Society of Environmental Toxicology and Chemistry (SETAC) and the International Organization for Standardization (ISO), but standardization of methodology assures neither meaningful results nor appropriate use of the results. This paper examines the types of analysis that are possible for automobiles, explains possible pitfalls to be avoided, and suggests ways that LCA can be used as part of a rational decision-making procedure.The key to performing a useful analysis is identification of the factors that will actually be used in making the decision. It makes no sense to analyze system energy use in detail if direct financial cost is to be the decision criterion. Criteria may depend on who is making the decision (consumer, producer, regulator). LCA can be used to track system performance for a variety of criteria, including emissions, energy use, and monetary costs, and these can have spatial and temporal distributions. Because optimization of one parameter is likely to worsen another, identification of trade-offs is an important function of LCA.