What are the key technological improvements?
The main contributors to truck fuel consumption are the powertrain, aerodynamics and tires. So this is also where the biggest potential for improvements lies.
Current truck engines are already relatively efficient. With a peak break thermal efficiency of around 45%, truck engines perform a lot better than passenger car diesel or petrol engines. But engine efficiency could be improved further still. For example, Cummins an American engine making company – says it could reduce fuel consumption through engine efficiency improvements by 5-11% compared to a current truck (2015 EURO VI truck engine).
The key features of a more efficient engine and drivetrain are related to improving the combustion process, air handling, friction and parasitic reduction, and last but not least waste heat recovery technology
Efficiency levels of 50% are achievable. But as part of the US supertruck programme truckmakers also had to show there’s a technically feasible pathway towards 55% engine efficiency and it is now assumed that with things like waste heat recovery this would be possible.
When a truck is driving on a highway, around 40% of the fuel it uses is goes to overcoming air resistance. So the more streamlined you make the vehicle, the less energy you need to move it. Aerodynamic improvements can be made to all parts of the truck: the front, the side and the back. Generally, better aerodynamics are seen as one of the most cost-effective ways to reduce truck fuel consumption and carbon emissions.
Tractor cab aerodynamics
Current EU trucks are brick shaped. This unaerodynamic shape was ‘forced upon’ truckmakers by the EU’s truck dimension rules.
The 16.5m length limit has encouraged truckmakers to maximise cargo space (trailer) and minimise tractor space. A rounder and more streamlined frontal design would improve aerodynamics and reduce fuel use.
The trailer accounts for 50% of the aerodynamic drag of a truck and there is a lot of potential for improvements to its current boxy design. For a good overview of what’s possible for the side and the back (i.e. the trailer) the PART Platform website is an excellent starting point. Key technologies here include side-skirts and aerodynamic flaps fitted at the back of the trailer.
Platform for Aerodynamic Road Transport – Aerodynamics studies
Truck and trailermakers too have demonstrated there’s a lot of potential for improvements.
For example, MAN built the Concept S which was completely optimised for better aerodynamics. Combined the tractor and trailer would be 15% more fuel efficient.
Tires play a major role in reducing fuel use from trucks. Overcoming so-called rolling resistance accounts for around 45% of fuel used. The use of low rolling resistance, single wide tires along with making sure tires are always well inflated can result in CO2 savings of 5% to 10%. The European tire label classifies truck tires from A to G. The difference between the best and worst is 7.5%. Currently most truck-trailer combination run on B-C label tires.
Keeping the tires well inflated is extremely important. Tire pressure monitoring systems (TPMS) can help fleets keep track of this. Fleet trials have demonstrated average benefits for HGVs at 3 – 4% fuel consumption reduction. TPMS is mandatory for passenger cars but not for trucks.
Driver training and telematics
Fuel consumption isn’t just about vehicle technology; it is also very much about how you use the vehicle. The way a truck is driven can make a difference of 15% in fuel use. That’s why many progressive trucking companies started training their drivers. Many companies go further still and actively monitor their drivers’ performance via so-called telematics (see for example MAN telematics). This allows fleets to compare the driving style and fuel use of their drivers. Some companies even create contests and reward so-called fuel champions, e.g. by giving them part of the money they’ve saved for the company as a bonus.