As with light duty vehicles, reduced tractive load can be achieved by lightweighting trucks so fewer trucks can carry more cargo. Lightening trucks has less benefit for mpg than in a car (20% of fuel energy moves cargo vs. ~0.3% for an auto), but greatly raises productivity for trucks with weighed-out loads.
Lightweight high-strength steel or alloys in different components throughout the tractor and trailer can save over 2,800 lb at a cost of $1–4/lb.
Vyas, A., C. Saricks, and F. Stodolsky. 2002. The Potential Effect of Future Energy-Efficiency and Emissions: Improving Technologies on Fuel Consumption of Heavy Trucks. Argonne, IL: Center for Transportation Research.