Mercedes CLA

The new CLA from Mercedes Benz exhibits an advanced aerodynamic design. With a coeffficient of drag of only CD=0.23 1 And a CD*A of 0.51 m2.

igure 1. CLA in wind tunnel with smoke injection showing flow streaklines [1].

Aerodynamic Feature Info/Notes
Aerodynamic wing mirrors
Wheel arch design Slotted wheel house liners and serrated wheel spoilers. The wheel spoiler is essentially a fancy wheel air deflector. Simplified versions of this device are used on many production cars, most often for the front wheels. According to Mercedes, the serrated design of their deflector helps to stabilize shear waves along with deflecting the flow around the wheels.
Underbody paneling Smooth flow below the car promotes energy recovery in the wake. This includes an engine cover, main cover (center of car) and even covers for the rear suspension components.
Specially designed A-pillars
Unique muffler shape  In most vehicles the muffler is a distinct unit that protrudes into the underbody flow (it is not recessed or inset into the underbody design). For the CLA the muffler is designed such that it is essentially an extension of the underbody cover. This promotes energy recovery in the wake.
Overall shape Proper shaping results in a tiny base drag.
Louvered-shutter in front of radiator Acts in the same way as the Ford active grille. A motorized shutter system is actively controlled to allow more or less airflow into the engine bay. This reduces engine-bay drag and optimizes cooling.


igure 2. CLA aerodynamic design features [1].