Truck fuel economy increasingly depends on small gains adding up
Reducing fuel consumption in heavy trucks increasingly depends on the cumulative effect of small technical improvements. Beyond the engine and aerodynamics, energy use is also influenced by the driveline, tyre rolling resistance, energy management and predictive driver-assistance systems.
At the same time, the European Union is tightening CO2 requirements for heavy-duty vehicles. Under the revised framework, most regulated vehicle subgroups are subject to CO2 reduction factors of 45% from 2030, 65% from 2035 and 90% from 2040. The exact reference values and compliance calculations vary by vehicle category.
The engine alone is no longer enough
The best heavy-duty diesel engines are now approaching 50% brake thermal efficiency. Scania, for example, quotes a peak brake thermal efficiency of 50% for its 13-litre Super engine. Manufacturers are pursuing further gains through more precise fuel injection, lower internal friction, more efficient turbocharging and operation at lower engine speeds.
At motorway speeds, aerodynamics has a major influence on fuel consumption. Roof and side deflectors, more aerodynamically optimised cabs and camera systems replacing conventional mirrors all help reduce drag. The benefit of any single change may be modest, but over a high annual mileage the combined effect of several improvements can become significant.
The same principle applies to the transmission. Scania's GW gearbox uses a range interlock that prevents simultaneous gear engagement and removes the need for a separate reverse gear. According to Scania, the design makes the transmission shorter and lighter while reducing energy losses.
Tyres and software also affect operating costs
With tyres, there is no meaningful single fuel-saving percentage: the result depends on the truck, its load, the road surface, tyre pressure and tyre construction. Continental nevertheless says rolling resistance can account for up to one-third of a truck's fuel consumption. Correct tyre pressures, proper wheel alignment and low-rolling-resistance tyres can therefore reduce energy losses directly.
Software is playing an increasingly important role as well. Predictive cruise control systems use topographic data to anticipate climbs and descents, adjusting speed, gear selection and coasting accordingly. According to Scania, its updated Cruise Control with Active Prediction can deliver additional fuel savings of up to 2% on undulating roads.
Heavy-truck fuel economy, then, no longer depends on a single breakthrough technology. Manufacturers are working in parallel to reduce losses in the engine, driveline, aerodynamics and tyres, while using more software to make those systems work together as a whole. For a high-mileage truck, the combined effect of several small improvements can translate into a meaningful reduction in fuel costs for the haulier.
