The electric car revolution is coming. Many manufacturers are readying battery-powered models and hybrids as the switch to eco-motoring becomes a reality.
But with that switch comes problems – and the biggest noises are being made about a silent issue: the lack of sound made by electric cars.
Granted, pedestrians listening to iPods and not paying attention deserve to be squished, but what about the blind? If they can't hear these cars coming there's potential for disaster.
Some car makers are planning to introduce artificial noises to warn those around that a car is approaching – but currently there are no legal requirements for it.
The EU is planning regulations that would set a minimum volume cars can make, but that's not yet been implemented – and with that comes another issue: What should electric cars sound like?
Audi is already looking to Hollywood for inspiration for its e-tron. Its acousticians are evaluating the noise made by the RSQ model from the film 'I, Robot' as one option.
We've asked a number of manufacturers currently producing, or preparing to launch, electric cars about their plans – and although it's clear the silence is an issue, a standard solution isn't apparent.
'The Tesla is not completely silent,' argued a spokeswoman. 'There's no engine noise, but you can still hear it coming down the road. We have no plans to add artificial noise, but we're paying attention to the conversation.'
Mini - which has conducted trials of its 'E' model – said it had a number of solutions.
'We are looking to add an artificial external soundscape should it prove necessary,' a spokeswoman told Autoblog. 'We are working with associations for the visibly impaired – there are a number of possible solutions.'
So the manufacturers that have launched models are aware of the problem, but what about those readying electric cars for sale? Is it an issue they're working to resolve? It's certainly something Steve Groves, an engineer working on the Nissan Leaf, is getting his head around.
'At an early stage in the development Nissan identified that this issue is important,' he explained. 'The Leaf makes two sounds in forward and reverse. The forward "authentic EV sound" operates up to 30kph at which point road noise is sufficient to warn that a vehicle is approaching. The reverse beeping sound operates whenever the car is in reverse.'
Groves revealed that during trials Nissan considered '80s synth sounds and even natural ones such as choir and bird song.
Renault said its electric cars – like the ZE – would also make artificial noises up to 30kph. Andy Heiron, head of the EV program, said: 'Renault is developing a vehicle sound pedestrian system for its electric vehicles which anticipates likely EU legislation.
'The sound is likely to be a synthesized, futuristic one, which in terms of technical characteristics is designed so it also allows the visually-impaired and their guide dogs to correctly judge the speed and acceleration of the car.'
Peugeot and Mitsubishi are jointly preparing the iOn / i MiEV electric car for sale next year. Peugeot said it was considering a 'pedestrian horn' which would be less aggressive than a standard one.
'We are also considering a generated noise at low speed. This solution, however, has the disadvantage of removing one of the benefits of an electric car – reduction in city centre noise pollution,' explained a spokesman.
Mitsubishi admitted it recognised the need for an artificial noise and was 'working on a solution'. While Vauxhall – due to launch the Ampera in 2012 – added that by the time its car was ready EU regulations on the matter would be clearer and it would have a 'solution'.
One thing was startling obvious from our investigation though – with no industry standard on the preferred artificial noise, the sound of motoring in the future could be very different to gentle hum of combustion we're used to now...