Hyundai, Kia Introduce 'Active Air Skirt' to Boost EV Efficiency

Automakers are looking for ways to reduce the coefficient of drag to maximize mileage range between charges.

The AAS system controls airflow through the lower part of the vehicle's bumper, specifically targeting the turbulence around the vehicle wheels.

Hyundai Motor Company and Kia Corporation introduced the "Active Air Skirt" (AAS), designed to minimize aerodynamic resistance during high-speed driving, thereby enhancing both the driving range and stability of EVs.

The AAS system controls airflow through the lower part of the vehicle's bumper, specifically targeting the turbulence around the vehicle wheels, varying its operation in response to the vehicle's speed.

Manufacturers worldwide are exploring various means to reduce the coefficient of drag (Cd), a measure of resistance against a vehicle's motion. Installed between the front bumper and wheels, the AAS system remains hidden during normal operation but activates at speeds over 50 mph, where aerodynamic resistance surpasses rolling resistance. The system retracts once the speed drops below 44 mph, a design choice made to avoid frequent activation in specific speed ranges.

The placement of the AAS is strategic, covering only the front part of the tires without full enclosure. This design decision stems from the characteristics of Hyundai Motor Group's E-GMP platform for EVs, focusing on enhancing aerodynamics by covering only the tire part, as the platform floor is already flat. This setup not only improves aerodynamics but also enhances the vehicle's downforce, thus improving traction and high-speed stability.

AAS can operate even at speeds over 124 mph, a capability made possible by the application of a rubber material on its lower part, reducing the risk of damage from external objects while driving at high speeds.

Hyundai Motor and Kia demonstrated the effectiveness of AAS in the Genesis GV60, showing a reduction in the drag coefficient by 0.008 and improving drag by 2.8%, which translates into an additional range improvement of approximately 3.7 miles.

The companies have secured patents for AAS in South Korea and the U.S. and are considering mass production following further durability and performance tests.

“This technology is expected to have a greater effect on models such as SUVs where it is difficult to improve aerodynamic performance,” said Sun Hyung Cho, vice president and head of Mobility Body Development Group at Hyundai Motor Group.

In addition to AAS, Hyundai Motor and Kia are incorporating various technologies like rear spoilers, active air flaps, wheel air curtains, wheel gap reducers and separation traps to achieve competitive drag coefficients. The Hyundai IONIQ 6, which integrates these technologies, has achieved a globally leading Cd of 0.21.

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