Smart changes in the aerodynamics of semi-trucks results in doubling their mileage. An Airflow Truck with a 65,000 lb. load averaged 13.6 from Connecticut to California, way up from the average 6 mph average. The truck has an aerodynamic nose, covered wheels, LCD readouts, hybrid air conditioning, and video cameras instead of mirrors. Replacing the mirrors with cameras alone resulted in a huge gain in MPG. Perhaps one day, all new vehicles will have cameras not mirrors. Think of the gas that could be saved.
Most truckers get a flat rate for a haul and pay for fuel themselves. Trucks like this are money in their pocket. Diesel currently averages $3.33 a gallon nationwide. A 3,000 mile cross country trip would use 220 gallons at 13.6 mpg vs. 500 gallons at 6 mpg – a savings of $932.