Aerodynamics: Playing with the wind

Jun 3, 2016

Low fuel consumption figures require good aerodynamic properties – one of the strengths of the C-Class Cabriolet.

Mercedes-Benz offers the most streamlined cars with the lowest drag coefficient in almost all vehicle categories. For the new C-Class Cabriolet it is 0.28 with a cross-sectional area of A = 2.19 m2.

 

C-Class Cabriolet

C-Class Coupé

Drag coefficient Cd

0.28

0.26

Frontal area (A), m2

2.19

2.18

Aerodynamic drag Cd x A

0.61

0.57

Because the aerodynamic drag is greater than all other driving resistance forces from a speed of about 70 km/h, this low figure for the Cabriolet pays off in the form of fuel savings and reductions in CO2 emissions – especially at higher speeds such as when driving on the motorway. A reduction of this value by 0.01 translates into one gramme less CO2 per km in the driving cycle (NEDC), while in average real-world consumption conditions it can equate to two grammes, and at 150 km/h actually to as much as five grammes of CO2 per kilometre.

Intensive detailed work for Cd benchmark

The aerodynamics engineers achieved the Cd value of the C-Class Cabriolet with an extensive package of measures. These include:

  • aerodynamically designed front and rear bumpers
  • aerodynamic wheel spoilers, at the front with 3D shape and auxiliary spoiler on the front engine bay shroud
  • sealing between wheel arches and engine compartment
  • aerodynamically designed exterior mirrors with mirror base
  • sealing around headlamps and aero lip in the gap between the bonnet and the front bumper
  • improved sealing of the radiator section and flow properties to make efficient use of the available cooling air
  • spoiler modelled on the boot lid
  • aerodynamically optimised underbody with extensive engine compartment and underbody panelling
  • aerodynamically optimised wheels and tyres
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