DesignBoom.com followed Audi sound engineers as they created a unique voice for the upcoming Audi E-Tron electric vehicle. The challenge was to create a unique sound for the car so that pedestrians could hear it coming. The electric motor that drives the car is almost silent at low speeds. The sound had to be unmistakable as an electric vehicle and change pitch with the motor rpm’s to give the impression of acceleration.

On a similar note, the sound given to The Batpod in The Dark Knight Rises is based off of a Tesla Roadster on a dyno. Director Christopher Nolan wanted the pod to sound like it was always surging and unstoppable.