An outstanding drag coefficient of cd = 0.26 places the new B-Class at the forefront of its market segment. With the optional ECO Technology package, which will be available at a later date, the five-door B-Class even achieves the world-class aerodynamic credentials of the E-Class Coupé, attaining a drag coefficient of cd = 0.24 which is nothing short of sensational for a vehicle with a station wagon rear end. In practical driving, aerodynamics have a crucial influence on fuel consumption: an improvement in the cd value of just 0.01 results in fuel savings of up to 0.4 litres per 100 kilometres at a speed of 130 km/h.
"A whole range of measures were necessary in order to attain the excellent drag coefficient of cd = 0.26," explains Dr. Teddy Woll, Head of Aerodynamics at Daimler AG. "Apart from an aerodynamically efficient basic design, these include numerous optimisation measures on points of detail, such as the air flow around the front wheels, the underbody design and the flow of cooling air."
Designers and aerodynamicists worked closely together. Aerodynamically efficient lines are demonstrated by the exterior mirrors with braces, for example. The low height of the shoulder on the A-pillar accompanied by optimised A-pillar geometry also contributes to the good aerodynamics. The entire front apron is sealed, including special seals fitted on the headlamps, for example. The large roof spoiler at the rear provides for defined flow separation.
Flow losses at the front wheel arches have been reduced substantially with the aid of innovative serrated wheel spoilers at front and rear - patent pending -, slots in the wheel arches and optimised hub caps. These measures result in improved wind flow around the wheel arches.
Equally comprehensive measures have been undertaken to design the underbody along aerodynamic lines. The main floor panel features extensive cladding up to the rear wheel arch, followed by additional cladding of the rear axle. The rear silencer has also undergone aerodynamic optimisation.
The improved cooling air flow by means of an adjustable radiator shutter which is familiar from other Mercedes models now features on the basic petrol-engine model in the B-Class. This feature enables infinite adjustment of the air flow through the engine's cooling module and the engine compartment by means of a circular louvred shutter installed in parallel with the fan. When there is no special need for cooling air, the shutter is closed. This improves the aerodynamics and reduces fuel consumption.
The ECO Technology package, which will be optionally available for all versions of the B-Class, incorporates additional optimisation measures designed to further reduce drag. These include lowering of the body, the sealing of joints at the rear window and the cladding of chassis components at the rear axle.
The aerodynamics of the new B-Class were optimised at an early stage in the development process by means of complex computer calculations and flow simulations. Over 275,000 CPU hours were required for the purposes of digital flow simulation. Models and prototypes spent around 1100 hours in the wind tunnel for measurement purposes.
Source: Daimler AG
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