The A-Class has best-in-class aerodynamics.
Dr Alexander Wäschle and his team achieved this
with a multitude of optimisations.
CO2 emissions (combined): 165-98 g/km*
Dedicated to efficiency:
Dr Alexander Wäschle.
Wäschle, who holds a doctorate in mechanical engineering, can be very proud of the new A-Class. The basic model, with a Cd value of 0.27, already sets a new benchmark, while the A 180 CDI BlueEFFICIENCY Edition manages to top even this record figure for a hatchback: thanks to a whole series of aerodynamic optimisation measures, this beacon of efficiency achieves a Cd value of 0.26. "The fact that the A-Class is the best in its class is not down to just one single innovation," he explains. "In fact it has been achieved through the systematic implementation of many smaller optimisation measures." What drives him in his work is a concern for the environment: "As an aerodynamic engineer, I am keen to play my part in making our vehicles even more fuel-efficient," emphasises Stuttgart-born Wäschle.
The effect is unequivocal: "An improvement of just one hundredth in the Cd value reduces the fuel consumption by a tenth of a litre per 100 km, travelling at a speed of 120 km/h," he explains.
Storm beaten: A-Class in the wind tunnel.
It is important to reduce the area of airflow resistance to an absolute minimum - "important to the power of two, because air resistance increases in direct proportion to the square of the vehicle speed." So, what are the specific measures that have helped produce such good results for the A-Class in the wind tunnel?
"The special features of this model series include the distinctive spoilers to either side oft he rear window," the engineer tells us. "These 'finlets' give rise to a wake pattern that significantly reduces the negative impact of the longitudinal eddies curling around the D-pillar."
The design of the underbody and of the cooling air flow has been improved, as has the dynamic flow around the front wheels. Serrated wheelarch spoilers front and rear, vents in the wheel arches and aerodynamically optimised wheel trim all contribute to significant reductions in airflow losses around the front wheel arches. As Wäschle tells us: "We have a patent pending on the wheel spoilers."
In their work to optimise the A-Class, Dr Wäschle and his colleagues have made more use of Computational Fluid Dynamics (CFD) than has been the case with previous model series: first of all, CFD was used to improve every single component in a series of simulation loops, before its aerodynamic characteristics were put to the test and measured in the wind tunnel.