A Southern California Edison employee logs test results at the company's electric meter site. (Corbis-Bettmann)

At the beginning of the twentieth century, the automobile was still a novelty. In the United States more cars were then powered by steam engines and battery-electric systems than by internal-combustion engines. By the end of the twentieth century, the automobile had become an integral part of the American lifestyle, with approximately one privately owned passenger vehicle in operation for every two people. Practically all of these vehicles were powered by internal-combustion engines burning a fuel derived from petroleum.

New cars are purchased on the basis of such qualities as performance, fuel economy, reliability, durability, ride quality, noise and vibration, comfort, convenience, maintenance requirements, styling, safety, environmental qualities, price, and resale value. Many of these attributes conflict. The conflict between performance and fuel economy serves as an example. The typical driver...