Feasible technological improvements in vehicle efficiency, combined with “long combination vehicles” (which raise productivity by connecting multiple trailers), can potentially raise the ton-mile efficiency of long-haul heavy tractor-trailers by a factor ~2.5 with respect to a baseline of 130 ton-miles/gal. Within existing technological and logistical constraints, these innovations (which do not include such further opportunities as hybrid-electric powertrains or auxiliary power units to displace idling) could thus cut the average fuel used to move each ton of freight by ~64 percent. This would annually save the current U.S. Class 8 fleet about four billion gallons of diesel fuel and 45 million tonnes of carbon dioxide emissions. Further benefits would include lower shipping costs, bigger profits for trucking companies, fewer tractor-trailers on the road, and fewer fatal accidents involving them. Thus transformational, not incremental, redesign of tractors, trailers, and (especially) both as an integrated system can broadly benefit economic prosperity, public health, energy security, and environmental quality.