How developing an extended truck cab has led to enhanced energy efficiency and energy savings

With its unique aerodynamic design, the Volvo FH Aero sets new standards in energy efficiency and aerodynamics. It is also the culmination of over a decade of research and development, and continuous refinements to develop the most fuel-efficient truck possible.

The most distinctive feature of the new Volvo FH Aero and Volvo FH16 Aero is the extended front, which represents a slight departure from the conventional cab-over-engine truck design. It also enables enhanced aerodynamic performance, and in combination with earlier improvements, the new range improves fuel efficiency by up to 5%*. This makes it Volvo Trucks’ most aerodynamic and energy efficient design yet.
 

“From an aerodynamics perspective, we want the corners to be as smooth and rounded as possible, but until recently we’ve been restricted by legislation regarding vehicle length,” says Anders Tenstam, Senior Technology Expert Aerodynamics, Volvo Trucks. “Now, we have the opportunity to extend the front of the cab and increase the curvature. This will not only improve the aerodynamics of the cab but also help maximize all the other improvements we have made across the whole vehicle.”

How looking long-term benefited aerodynamic development

While the extended front has been enabled by changes to EU legislation regarding truck length, the origins of the Volvo FH Aero go back much further. In fact, Volvo Trucks’ engineers have been exploring new concepts and ideas for improving the Volvo FH for over a decade. The first step was to create a separate entity internally, which focused on advanced engineering. Rather than look into making small, isolated incremental improvements for immediate launch, the new team’s directive was to take a long-term, holistic approach to the whole vehicle.
 

“We typically try not to restrict ourselves too much because it's really important that you create space for new ideas to come to the surface,” says Anders. “If you’re working with multiple projects according to strict time plans, then you need to prioritize, and typically the long-term advanced engineering suffers. Instead, we take a broader approach and try to explore different concepts concurrently, which we can later combine to create a solution that is greater than the sum of its parts.”

How a decade of research came together

Central to Volvo Trucks’ approach to aerodynamics is the streamline principle, where all the different sections of the vehicle are seen as interconnected and dependent on each other. In other words, aerodynamic improvements towards the back of the vehicle will have an even bigger impact if the aerodynamics at the front have been optimized.

“If you make the front more aerodynamic, that means that the air flow tucks in closer to the body of the truck, which means that downstream improvements will pay off even better,” explains Anders. “Conversely, upstream improvement could partly be cancelled out by any imperfections further downstream. This is why it is difficult to isolate single changes and expect them to make a big difference. Instead, you need to think of aerodynamics as a package.”
 

Perfecting all of the different components has been Volvo Trucks’ focus since 2012, and many of its aerodynamic concepts were already introduced in 2022. This includes additional sealings on split lines on the front of the cab, closure of the footstep, and a closer wheel arch perimeter.
 

The EU’s legislation permitting longer cabs was first mooted in 2013, before coming into force in late 2019. Because of its long-term approach, Volvo Trucks was able to anticipate the upcoming legislation and explore the possibilities it would open up in terms of cab design early on. As such, the new extended front cab has been developed in conjunction with these earlier improvements. In fact, it helps enhance these features further and completes the package. “It’s a case of 1 + 1 = 3,” says Anders. “Each of these aerodynamic improvements alone will generate fuel savings, but when you bring them all together, the total savings are even greater still.”
 

What additions can be made to further improve energy efficiency? 

In addition to the extended cab, the Volvo FH Aero is also available with the new Camera Monitor System, which essentially replaces the side mirrors with wing-shaped cameras. As a result, one of the main obstacles to air flow on the vehicle’s sides is eliminated.
 

“Since the backside of a mirror needs to be flat, creating a wake zone behind it is unavoidable, so it will always contribute aerodynamic losses,” says Mattias Hejdesten, Senior Engineering Expert Aerodynamics, Volvo Trucks. “But by replacing it with a smaller camera lens, it becomes much easier for the air flow to stick closer to the vehicle’s body.”

When it comes to traditional aerodynamic aids such as roof and side deflectors, spoilers, fenders, chassis fairings and wheel caps, these remain important when it comes to maximizing fuel efficiency. Volvo Trucks has also recently developed an additional aerodynamic aid for its air-suspended chassis: an automatic function for reducing ride height at speeds over 60 km/h.
 

“Now that we have optimized the front of the vehicle with the extended cab, we need to ensure the downstream areas are optimized too, and here we rely on spoilers, fenders and extended chassis fairings to help keep the air flow attached to the side of the vehicle,” says Mattias.

How does extending the cab impact electric trucks?

Both the gas-powered Volvo FH Aero and Volvo FH Aero Electric enjoy similar benefits to an extended cab in terms of energy efficiency. However, when it comes to the Volvo FH Aero Electric, the potential gains are larger still due to the recuperation system utilized in an electric driveline. “Electric trucks recuperate energy every time they brake, which is fed back into the system rather than lost,” explains Mattias. “Since lower drag leads to greater pedal brake energy when braking, the recuperation system will be harvesting more of such energy into re-generated electric power. So, the relative payback from an extended front cab is even better than with gas or diesel.”

For an electric truck, increased energy efficiency translates into extended ranges, which is one of the biggest limitations to using an electric driveline.

_{* Actual fuel economy may vary depending on many factors i.e. driving speed, use of cruise control, vehicle specification, vehicle load, actual topography, the driver´s driving experience, vehicle maintenance, and weather conditions.}