Vehicles are already labeled for efficiency based on city and highway fuel economy estimates. The direct impacts of any of the elements of a Green Machine Challenge would be small in the context of overall national energy use and greenhouse gas emissions. Stronger CAFE standards, or equivalent regulatory pressures linked to vehicle CO 2 emissions, would be needed to ensure significant fleetwide fuel economy improvements. Given the caveat that one cannot reliably project benefits from a program such as this, plausible scenarios can illustrate the possible impacts of a Green Machine Challenge. Our range of estimates is summarized in the adjoining table.
Cost estimation is also highly uncertain.
The potential value of a Green Machine Challenge should not, however, be evaluated only on the basis of impact estimates for even an ambitious program such as that outlined here. A market creation initiative is but one component of a broader market transformation strategy for motor vehicles. Working together, such an array of policies could have enormous impact, leading to widespread adoption of new-generation vehicle technologies that could go a long way toward mitigating the fuel consumption related problems of cars and light trucks. Thus, such a program could begin to engage competitive forces in the service of environmental goals. The resulting change in attitudes about what is valued in a vehicle, by both automakers and consumers, would be profound, and could prove to be a crucial turning point down a road that leads to an environmentally sustainable transportation system for generations to come.