Vroom vroom - a noisy car engine is not often the most welcome sound but it can be a life-saver, especially for the visually impaired.And now Norfolk company Lotus has recognised the possible danger of its absence in electric or hybrid cars, sparking a project to synthesise the sound of a traditional engine in otherwise quiet vehicles.

Vroom vroom - a noisy car engine is not often the most welcome sound but it can be a life-saver, especially for the visually impaired.

And now Norfolk company Lotus has recognised the possible danger of its absence in electric or hybrid cars, sparking a project to synthesise the sound of a traditional engine in otherwise quiet vehicles.

Lotus Engineering, the car manufacturer's consultancy division yesterday revealed technologies developed by experts to synthesise external sound and address the growing concern about the danger posed to pedestrians and cyclists by quiet cars.

A simulation of a real engine sound is used on the Safe and Sound hybrid technology demonstrator vehicle, making it instantly recognisable that the vehicle is in motion.

Despite their environmental credentials, electric and hybrid vehicles have come in for criticism from blind and partially sighted people due to their almost silent operation.

Mike Kimberley, chief executive officer of Group Lotus, said: “The increased acceptance of greener vehicles such as hybrid and electric vehicles is to be encouraged; they have an important role in improving fuel econo-my and reducing emiss-ions.

“Our advanced external sound synthesis technology increases pedestrian safety, while retaining the car's environmental benefits. We hope that legislators introduce minimum noise require-ments for vehicles to encourage the adoption of technologies, such as ours, which will ultimately increase pedestrian safety.”

Clive Wood, transport policy officer at the Guide Dogs for the Blind Association, said: “Blind and partially sighted people use the noise of oncoming traffic as a cue for when it is safe to cross a road - if a 'quiet' hybrid electric vehicle is approach-ing then they will no longer have this cue and are immediately put at risk.”

The technology demonstrator uses a standard Toyota Prius, one of the most advanced hybrid vehicles, to demonstrate the sound synthesis application and compensate for the lack of engine noise when running on an electric motor.

Duncan Vernon, road safety manager for the Royal Society for the Prevention of Accidents, said: “We welcome innovative solutions which address this.”