STUTTGART, Germany – At the Daimler factory in Stuttgart, Germany, sound engineers have been tasked with making electric cars sound, well, more like gasoline-fueled vehicles, Bloomberg News reports. At low speeds, electric cars issue practically no sound, creating a hazard for bicycle riders and walkers tuned to gasoline-powered engine noises.

Sound engineer Christoph Meier created a “sonorous purring” for the company’s e-Smart city car, while the Mercedes SLS AMG Coupe Electric Drive has acquired a huskier sound. “People expect some exterior noise from a vehicle, because we all grew up with the ‘vroom vroom’ of combustion engines,” said Meier, who supervises the power-train acoustics team at Daimler, which owns Mercedes.

Other automobile makers have been adding sound to their silent electric models. Renault has a trio of sounds for its Zoe hatchback: glam, pure and sport. Nissan’s Leaf, which ranks as the number-one selling electric vehicle — has a man-made tone to its engine.

The car manufacturers are not just whistling in the dark, but are aiming to get ahead of anticipated regulations this year that would require warning sounds from the otherwise silent electric cars. The European Union has already proposed a measure that would require sounds to warn pedestrians and others, especially the blind and visually impaired, who have grown used to hearing acoustic noises from cars.

“If a silent electric vehicle knocks over an elderly person or a child, it’s not worth the risk,” said Neil King, an analyst with Euromonitor. “It happens often enough in urban areas that people are stepping into the road without looking. You can’t get around that.”