The American trucking industry moves 60 percent of America’s goods using 3.5 million tractors and 5.3 million trailers. Yet despite their ubiquity, tractor-trailer designs have remained fundamentally unchanged for fifty years. Within the trucking industry, long-haul heavy-duty (Class 7 and 8) trucks offer particularly great efficiency potential. Despite accounting for less than half of the nation’s trucks, Class 7 and 8 trucks account for almost 80 percent of trucks’ fuel consumption. Their size, speed, and poor aerodynamics mean Class 7 and 8 trucks are laden with “low-hanging fruit” (cost-effective efficiency and retrofitting opportunities). According to a recent analysis by Rocky Mountain Institute, the technology already exists to double trucking efficiency.