t is important to study the full effect of any vehicle design, especially when promoted as better than the status quo. The goal may be to look at overall efficiency only or it may be the total environmental impact, since environmental damage reduction is often the goal behind alternative vehicle efforts. Many factors must be considered when making an overall comparison of total environmental impact. The most comprehensive comparison is known as a cradle-to-grave or lifecycle analysis. The analysis considers all inputs including original production and fuel sources and all outputs and end products including emissions and disposal. The varying amounts and types of outputs and inputs vary in their environmental effects and are difficult to directly compare. For example, are the environmental effects of nickel or cadmium contamination from a battery production facility less than those of hydrocarbon emissions or from petroleum refining? If so, how much, or how much of each would be equivalent? Similar types of questions would need to be resolved for each input and output in order to make a comparison.