Aerodynamics: Reduced resistance

Mar 9, 2016
Outstanding fuel consumption figures require great aerodynamic properties. The new E-Class has the lowest drag coefficient in its segment. At the same time, the aerodynamics engineers have minimised the wind noise, thereby making the E-Class the quietest saloon in the executive class.
From a speed of about 70 km/h, the aerodynamic drag exceeds the sum total of all other driving resistance factors. Therefore, reducing the drag also helps to lower the fuel consumption and CO2 emissions. The metric for aerodynamics is the Cd value. Lowering it by 0.01 means one gram of CO2 per km less in the driving cycle (NEDC), while, in terms of average real consumption, it means two grams. Progress on the aerodynamic front has an even more significant effect at higher speeds – especially when driving on motorways. A Cd jump from 0.25 to 0.23 produces a fuel saving of around 0.3 litres per 100 kilometres at a constant 130 km/h.
Mercedes-Benz is setting the pace in the field of aerodynamics and delivers cars with the best drag coefficients (Cd values) in almost all vehicle classes. The new E‑C lass also follows this tradition: the saloon achieves a drag coefficient of from Cd = 0.23, which makes it the benchmark in the executive class.
Although the frontal area (A) of relevance for drag has risen in the new E-Class from the 2.31 square metres of the previous model series to around 2.33 square metres on account of the increased exterior dimensions, this is more than made up for by the reduced drag coefficient. The drag area (Cd x A) is 0.54 m2, which means that it has been reduced by almost seven percent in comparison with the previous model.
New E-Class
from 0.23
from 0.25
A m2
Cd x A m2
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 example, in addition to the AIRPANEL air control system familiar from the C‑Class (opens and closes the radiator grille while driving by means of adjustable louvres depending on the required cooling), there is, for the first time, a second shutter in the front apron in the air inlet below the number plate. This considerably improves the overall performance of the system.
Further detail measures include:
  • aerodynamic design of front and rear aprons
  • wheel spoilers at front and rear
  • sealing between wheel arches and engine compartment
  • new exterior mirrors with mirror base
  • extended peripheral sealing of the headlamps with a tight connection to the radiator grille
  • aero lip in the bonnet/front bumper joint
  • improved sealing of the radiator section and flow properties to make efficient use of the available cooling air
  • integral design of the spoiler lip at the rear, taking account of the boot lid and tail light geometry
  • optimised underbody panelling concept with larger covers in the area of the front engine compartment
  • aerodynamically optimised wheels and tyres
Best-in-class aeroacoustics
A special focus of the aeroacoustics development work was to minimise the wind noise. For example, door/window seals were carried over from the S-Class in order to reduce the high-frequency components of the wind noise. Effective noise insulation also plays a major role in the extraordinarily quiet interior. Optionally available laminated safety glass in the Acoustic Comfort package can lower the wind noise even further.
The result is in terms of wind noise, the new E-Class occupies the top position in its segment and is thus the most comfortable long-distance executive saloon. On the wind noise front, it even surpasses many premium luxury-class saloons. This allows effortless in-vehicle entertainment, listening to music, telephoning, use of LINGUATRONIC, including at high speeds.