Ram Trucks has managed to eek out another mile per gallon from the already fuel-efficient Ram 1500 EcoDiesel pickup, proving the Detroit Auto Show wasn’t all about brawny off-road trucks. Ram’s new class-leading numbers are EPA-certified at 21 mpg city, 24 mpg combined, and 29 mpg highway. The upgraded mileage comes thanks to the HFE, or High Fuel Efficiency package. But technically, the Ram HFE is no different than any other Ram EcoDiesel, including its engine, transmission, and gearing specifications. It all comes down to equipment packaging and aerodynamics.