Aerodynamics in electric cars: Nature as a model

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As long as gasoline was cheap, the so-called cd or coefficient of friction did not matter to an ordinary car driver. But with the transition to electric drives, it is now decisive because of its impact on actual consumption. Because if a car doubles its speed, air resistance will increase four times and fuel consumption will increase tremendously.

This is why aerodynamics is becoming one of the most important disciplines in automobile development. Mercedes put an exclamation point last year with its upcoming work, the EQXX. Thanks to the sensational drag coefficient of 0.17 (see box), the prototype reaches record distances of around 1200 kilometers on one battery charge. “The technology program behind the Vision EQXX will redefine the models of the future,” explains Markus Schäfer, Member of the Management Board for Mercedes Development. At the beginning of 2025, the current Mercedes CLA will have a successor that will also set the best values ​​in terms of air resistance.

Thousands of tests required

Mercedes has already achieved this with the luxury model EQS. The lines that arc from the front hood to the tail tail may take some getting used to, but are extremely productive. The developers spent countless hours in the wind tunnel for the EQS series model. Thousands of tests were run on the computer, directing airflows, minimizing gaps and flattening the underbody. “In conclusion,” Markus Schäfer proudly says, “with a drag coefficient of just 0.20, the EQS is currently the most aerodynamic production vehicle in the world.”

Thus, the Mercedes EQS is almost at the level of the old small series model VW XL-1. Nearly a decade ago, the small eco flounder with a plug-in hybrid drive countered the oncoming wind almost imperceptibly with a drag coefficient of less than 0.19; this meant less than one liter of diesel consumption per 100 kilometers.

Form follows function

In addition to Mercedes, Hyundai consistently follows the maxim “Forms follows Function” (in German: Form follows function). The teardrop-shaped mid-range model Ioniq 6 achieves a maximum range of over 600 kilometers, despite a battery with only 77 kWh, thanks to a friction coefficient of 0.21. “In an electric car, aerodynamics is more important than anything else,” says Hyundai design chief Simon Loasby. And it turns out that the aerodynamic concept of the Ioniq 6 is based on aircraft engineers’ legendary vehicles from the 1920s and 1930s, such as the Stout Scarab, Phantom Corsair or Saab 92.

The Hyundai Ioniq 6 reduces air resistance with special rims that reduce the gap between the tires and the body, aerodynamic airflow through the wheel arches (air curtains) and caps on the wheel arches. With similar ideas, VW has reduced the drag coefficient to 0.23 for its new ID.7 electric flagship. When it comes to aerodynamics, it’s not just the hood, underbody panels or intricate air ducts that play a role. Tire manufacturers also work on their tires so that the side profile or lettering offers as little air resistance as possible.

What’s surprising: The Ioniq 6’s slim, optional side mirror cameras bring a range of just three kilometers more than conventional rear-view mirrors. Side mirrors with cameras, which take some getting used to, are likely to disappear as soon as they appear, not only in Hyundai, but also in other brands.

Source: Blick