What can this achieve?
Typically, a vehicle fitted with good aerodynamic styling features and devices can save between 6-12% of
the fuel used on long distance operations when compared with a vehicle having no aerodynamic features.When a vehicle moves through the air, the air exerts a force on the vehicle opposite to its motion. This force is known as aerodynamic drag. Large goods vehicles tend to have large relatively flat front ends and, in many cases, large flat rear ends. Flat surfaces being pushed through the air tend to suffer greatly from air drag and create considerable air turbulence around the vehicle. Aerodynamic drag can be considered as increasing with the square of speed making drag much more of a problem on long distance vehicles than on local delivery vehicles being operated largely within urban areas.Vehicle manufacturers do add some design features that are primarily to reduce aerodynamic drag but in the case of larger commercial vehicles being supplied as chassis cab, the base vehicle manufacturer cannot consider the type and design of body to be fitted. A range of additional drag reducing add-ons are available for retro fitment following completion of the body build.The shape and nature of the body can have a significant effect on the overall drag coefficient of the vehicle, and this should be considered at the design stage. Small changes such as rounding sharp edges whilst making little effect to carrying capacity can improve life fuel requirements. Any savings in fuel usage equate to savings in environmental emissions as well as reduced costs of operating the vehicle.The most favourable conditions for reducing aerodynamic drag are;
- Constant speed travel – on longer trunking roads
- Keeping the frontal area of the vehicle as small as possible, a large frontal area creates aerodynamic drag
- Retrofitting side panels which cover gaps and reduce airflow between the front and rear tractor wheels
- The lower the height of a trailer or load, the more aerodynamic drag will be reduced
Click here to see examples of aerodynamic devices and how they each reduce drag and improve fuel efficiency.
The use of other add-ons such as roof mounted air horns, and spot lights, should be considered carefully as these items are likely to increase drag and hence fuel usage.
When considering open bodied trucks, the position of the load in relation to the cab can make an appreciable difference to the drag coefficient of the vehicle. Account must be taken of axle loadings but where possible keeping the load as close to the cab of the truck will be beneficial in terms of drag and therefore fuel consumption.
Drawbar combinations will benefit from having a drawbar configuration that results in the gap between drawing vehicle and trailer being as small as possible.
Reducing the speed of a vehicle can have a very significant effect on fuel consumption. On a typical articulated vehicle spending much of its time at 56mph on the motorway, reducing the speed limiter setting from 56mph to 50mph can achieve up to around 10% fuel savings together with a corresponding decrease in environmental emissions.