Good fuel consumption figures require good aerodynamic qualities. With a c_d figure from 0.25 the new A-Class is better than its already very good predecessor (c_d figure: from 0.26/frontal area: 2.20 m²) – in spite of the increased exterior dimensions and the high model variance.

With a c_d figure from 0.25 and a frontal area (A) of 2.19 m², the new A-Class is the aerodynamic leader in its segment. To achieve this goal, the aerodynamics engineers have performed intensive detail work during computer-based airflow simulations and optimisations in the wind tunnel and, based on the results, implemented a series of effective measures.

For the first time in the compact class, Mercedes-Benz uses a two-section AIRPANEL (optional). This louvre system behind the radiator grille opens its adjustable louvres depending on the cooling requirement. There is an additional louvre system in the air inlet below the registration plate, which further improves system performance.

The front and rear wheel spoilers have been specifically optimised to achieve low airflow losses around the wheels. In addition the wheel arches are insulated from the engine compartment (depending on engine variant) and the radiator surrounds are sealed. This ensures more precise direction of the cooling air and a more efficient cooling system.

Further detailed aerodynamic measures include:

• sealed headlamp surrounds
• new exterior mirror on the beltline
• aero lip in the bonnet's joint to the front apron
• large roof spoiler, side spoiler, spoiler lips in the tail lights (standard) and on the rear bumper reduce air resistance and lift
• underbody panelling with large engine compartment, main floor, rear axle and diffuser panels
• improved shape of the rear exhaust silencer and heat shield (petrol engine)
• aerodynamically optimised wheels and tyres

Wind noises have been considerably reduced in the new A-Class compared to its predecessor. This was made possible by improvements in several areas. Sources of low-frequency noise were first identified with the help of numerical simulation, and reduced in effect by design measures before detailed fine-tuning on the test benches.

Where the high-frequency wind noises are concerned, particular attention was paid to the shape of the A-pillars in conjunction with the new exterior mirrors on the beltlines. The exterior mirrors were optimised in shape and position. The result was a reduction in wind noise and air resistance. Further important improvements were achieved in the design of the seals in the windscreen surrounds and the sealing of trim elements and detachable parts.