The automobile is the defining technological artifact of the twentieth century. Its familiarity, however, belies its complexity. It is no mean feat to design a car that is fast and powerful yet comfortable and safe-and still affordable. Factor in a few more constraints-durability, ease of repair, enough room for a few kids and the family dog, and an ample power supply for the electric windows, air-conditioning, CD player, and heated seats-and the challenge becomes clear. Precisely because the automobile has become an integral part of our lives, consumer expectations establish a set of formidable and often conflicting design objectives.

Over the last 25 years, automakers have faced growing pressure to incorporate environmental objectives into their designs as well. In particular, consumers and the federal government have pushed for improvements in fuel economy as a way to conserve oil and control pollution. The automobile industry has responded: the gas mileage of the average new car rose from 14.2 to 28.2 miles per gallon between 1974 and 1995.