Guest Editorial: Reinventing the Wheels

duty vehicles are amazing artifacts, made by the world's largest industry and fueled by the second-largest. American automakers make a new light vehicle every 2 seconds. Cheaper per kilogram than a fast-food hamburger, those vehicles meet conflicting requirements for performance, emissions, fuel economy, esthetics, and safety with remarkable skill. Yet, a typical light vehicle releases its own weight in carbon dioxide annually, and each day it consumes gasoline made from about a hundred times its own weight in ancient plants (Lovins et al. 2004). Cars and light trucks use 42% of America's 10,000 gal/second oil habit and account for 58% of projected growth in U.S. oil use to 2025 [Energy Information Administration (EIA) 2004]. At the root of the problem is technology that has improved only incrementally, not radically, since the 1920s. After more than a century of devoted engineering effort, today's cars use < 1% of their fuel energy to move the driver: only 13% of the fuel energy reaches the wheels, and just 6% accelerates the vehicle, 95% of whose weight is its own, not the driver's. Two-thirds (or, not counting accessory loads, three-fourths) of the fuel use is caused by the car's weight (An and Santini 2004), and each unit of fuel saved at the wheels saves an additional seven units of fuel lost en route to the wheels. Obviously, then, the most powerful way to reduce fuel use and emissions of cars is to reduce their mass radically—say, by half. Automakers have not yet taken this approach very seriously because they assumed reducing mass meant using light metals such as aluminum and magnesium, whose cost is barely justified to save gasoline that in the United States costs less than bottled water, and because they thought lightweighting would compromise safety in collisions with heavier vehicles. Fortunately, these objections are now fading. Both carbon fiber composites and light, high-performance steels now hold promise of equal or better economics and safety with roughly redoubled fuel economy—after it has already doubled by today's best hybrid-electric powertrains (Holzman 2005; Lovins and Cramer 2004; Lovins et al. 2004). Moreover, even the relatively costly advanced composites may not make cars costlier: the cost of their extra materials can be offset by simpler automaking and smaller power trains (Lovins et al. 2004). Thus an ultralight hybrid-electric vehicle could cost slightly more because it is a hybrid, but not because it is ultralight, and it …