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The sound of silence

Daimler electrics get fake vroom

Published: January 1, 2014, 2:00 PM
The e-Smart city electric car gets a "sonorous purr" with a higher pitch than conventional vehicles, and the $500,000+ Mercedes SLS AMG Coupe Electric Drive gets a husky roar, but both are part of a cresting wave of fake sound coming out of auto engineering studios worldwide. Mercedes' powertrain acoustics department alone employs 250 people at its Stuttgart, Germany facility.

It goes against the traditional function of luxury car acoustics engineering, where the goal is to make them glide along in near silence, but with silent electric vehicles posing a sneaky threat to pedestrians, manufacturers these days are reversing the process and inserting sound where none exists.

Bloomberg news reports that Renault SA offers a choice of tones, dubbed pure, glam and sport, on its Zoe hatchback, while the Nissan Leaf gets a fake sound of its own. Regulators are looking at ways to require warnings as soon as next year with manufacturers producing silent electrics in increasingly significant numbers. Bloomberg suggests that a spate of silence-related incidents involving pedestrians and cyclists could dampen demand in the sector, which is already struggling for popular approval. At the same time, their soundlessness is a competitive advantage makers are reluctant to give up.

Daimler's electric Smart offers an engine tone as standard in the U.S. and Japan, and as an option in Europe; the sound cannot be disabled by owners, unlike Renault, which lets buyers of its Zoe, Kangoo and Twizy electrics shut their sounds off if desired.

Tesla CEO Elon Musk said in June that electrics should emit a pleasant tone as a gentle warning rather than be required to emit a sound at all times. Smart's sound mimics the noise of a combustion engine, and even gets louder when the driver presses down the pedal.

“Simply imitating the sound of a combustion engine was not an option,” said Ralf Kunkel, head of acoustics at Audi, who developed a tone for the A3 E-tron plug-in hybrid, which debuts next year, as reported by Bloomberg. “We discarded ideas of giving electric vehicles sounds such as birds twittering or leaves rustling.”