A truck design developed by Cummins and Peterbilt gets 9.9 miles per gallon in real life tests, way better than the 5.5 – 6.5 trucks average now. This is a huge improvement in mileage, and could lead to much less diesel fuel being used by truckers nationwide as well increased profits for truckers, who are often independents paid a flat rate and who personally pay for the fuel.
The efficiency improvements were achieved using a more efficient engine, a waste heat recovery system, electronics that choose the most efficient routes for drivers, low-rolling-resistance tires, weight reductions, and a more aerodynamic chassis.
These are not exotic or expensive improvements and could easily be implemented on next-gen trucks.