Volvo Trucks Global
Volvo Trucks Global
How to choose the right aerodynamic fittings for your operation

How to choose the right aerodynamic fittings for your operation

Aerodynamic devices can save a typical long-haul operation as much as 10%* in fuel consumption. But it’s not just long-haul heavy duty operations with standard trailer configurations that can benefit. Other segments, including tank transport and construction, can also enjoy significant fuel savings with the right aerodynamic fittings.

Aerodynamics play a crucial role in the development of the truck cab design, but it is also possible to fit your vehicle with a range of additional fittings to minimise air resistance, and subsequently lower fuel consumption and CO2 emissions. To start with, I would like to touch on the different devices available and how they reduce air resistance and, in turn, save fuel.

Roof spoilers

Roof spoilers

When fitted correctly, the roof spoiler or deflector will provide the highest fuel savings of all the aerodynamic devices. Without it, the non-aerodynamic structures of the cargo bodywork are exposed to the oncoming air flow. The higher the cab and trailer on a truck, the greater the air resistance. The roof angle is also important. Adding a roof deflector can save you 5% in fuel when travelling at higher speeds, but it’s important to have it set according to the vehicle’s height. Even a few centimetres too low or high will reduce your potential savings. Your handbook will give detailed instructions on how to set the roof deflector for your specific truck variant. It may be a small effort to do it, but the potential savings are truly rewarding.

cab side deflector

Cab side deflectors or extenders

Developed to suit the cab design, cab side deflectors are especially suitable for tractors, but they are also useful for rigids and can be combined with all cab types. They help smooth the airflow from the cab around the sides of the trailer, reducing the amount of turbulence between them. Side fairings can also help to save fuel and are very important at higher speeds.

Chassis skirts

Chassis skirts or fairings

Chassis skirts cover the non-aerodynamic components that sit on the frame sides of the truck. They serve to smooth gaps out, reducing air resistance and lowering fuel consumption.


Fender Flares

These cover the gap between the front wheels and the surrounding bodywork to ensure that the swirling and turbulent air flow in the wheel house has a minimal impact on the external airflow. They come in a universal size but there is usually an option to upgrade them depending on the width of tyre you choose for your truck.

Bumper spoiler

Bumper spoilers

The bumper spoiler is fitted below the bumper to work as an air deflector and redirect air flow from the non-aerodynamic underside of the truck and trailer.

There are also measures you can take to improve the aerodynamics of your trailer, such as keeping the gap between the trailer and cab as small as possible, provided the permissible axle loads are respected. A trailer with covered sides will have lower fuel consumption than one without.

Aerodynamics and truck speed

Traditionally, the use of additional aerodynamic devices is the norm in the long-haul segment. This is because air resistance increases progressively with speed. As a rule of thumb, the air resistance increases fourfold when you double your speed. While I believe most operations can benefit from aerodynamic fittings, you do need to consider the route, average speed and the weight of the truck. There are some business areas where they are often overlooked without good reason, such as the tank transport, tipper and construction segments. In these applications, simulations typically prove that aerodynamic fittings will save a significant amount of fuel, even if the bodywork is lower in height than the truck. This is because the cab shape itself is not capable of shielding off the oncoming air effectively. Air deflectors are designed for this purpose and are just as relevant in these segments.

Weight vs. Payload

Finally, it is worth noting that in some segments, such as tank transport, there is a balancing act between the additional weight of aerodynamic devices (and the benefits they provide), versus the highest possible payload.

*The fuel improvement claim is calculated by comparing costs of diesel of a truck without aerodynamic options and features and one with. Calculations are made through vast simulation efforts as well as comprehensive tests in a wind tunnel and on the road. 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.

To address and understand these issues, and help you decide on the right aerodynamic fittings for your operation, I have prepared a guide that outlines the different parameters to consider when assessing your options.

Download the guide now!
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