When you think of Lotus one of the first things that comes to mind is the throaty growl of their engines but now the company is offering... silence.
It's developing technology that will produce the sound of a conventional combustion engine from under the bonnet of eco-friendly vehicles to make these ultra-quiet cars safer for unsuspecting pedestrians - particularly the blind - and cyclists.
One US study found hybrid and battery vehicles cars moving slowly had to be 40 percent closer to pedestrians than conventional cars before they were noticed.
Stealthy hybrids and battery cars have been criticised by groups representing the blind and partially sighted, concerned that they put pedestrians with imperfect sight at greater risk of being knocked down.
Lotus says its "safe and sound hybrid technology" simulates the sound of a combustion engine, making it "instantly recognisable that the vehicle is in motion".
It has already fitted the system to a Toyota Prius; it kicks in automatically to produce an artificial engine noise when the hybrid car switches to its electric motor. When the car's combustion engine takes over sensors fitted to the engine and suspension turn off the sound.
The engine noise is produced by a waterproof speaker next to the car's radiator, at a pitch and frequency designed to help pedestrians identify the car's speed and distance.
Lotus chief executive Mike Kimberley said: "Hybrid and battery vehicles play an important role in improving fuel economy and reducing emissions; our technology increases pedestrian safety, while retaining the car's environmental benefits."
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.
"They are immediately put at risk when a quiet hybrid or battery vehicle is approaching.
"We recognise the environmental benefits of these vehicles," he added, "but more consideration needs to be given to the safety implications to visually impaired pedestrians." - The Independent, London