The Leaf’s headlights are dramatically designed to direct airflow away from the wing mirrors. Through aerodynamic testing the workers realised that at high speeds the direction of airflow caused a high pitch whistling sound that could be heard very distinctly inside the car.
Typically, this would not be an issue as the sound of a petrol or diesel engines would naturally cover the sound of the whistling. Therefore, Nissan had to redesign the headlights so the airflow would be directed away from the wing mirrors to prevent any irritating sounds, which could potentially detract customers from purchasing the car.
With today’s technology, Nissan could use simulation software such as STAR-CCM+ to do CFD modelling on the airflow. This is both cost effective and intuitive design.