in a few years, the government will require electric cars and gasoline-electric hybrids to emit some type of noise at low speeds, when their battery-driven motors usually run silent. The promised rules—aimed at making the vehicles safer for vision-impaired pedestrians and others who rely on aural cues—have launched auto makers on a quest for the perfect sound.
Among those considered: noises reminiscent of jet engines, bells, birds, flying saucers and revved-up sports cars.
In developing their electric car, the Leaf, Nissan Motor Co. marketers initially saw the false-sound feature as a branding opportunity, a chance to create a distinctive sound, like a Jetsons jet pack, that would identify an approaching vehicle as a Leaf.
The near-silence of a battery-powered car is a point of pride for many hybrid drivers, an illustration of its ability to run at speeds of 40 mph or more without burning fossil fuel. The quiet ride has been a marketing point for auto makers, who spend millions on insulation and sound-damping technology to make cars quieter.