By: Michael Savage, The Independent
Thursday, 7 August 2008
Lotus is developing technology that will put the roar of the traditional combustion engine under the hoods of eco-friendly vehicles, in an attempt to make the quiet cars safer for unsuspecting pedestrians – particularly the blind – and cyclists.
Stealthy hybrids and electric cars have come in for criticism from groups representing the blind and partially sighted, concerned that the low hum of the vehicles puts those with imperfect sight at greater risk of being hit on the roads. Some are almost silent at slow speeds.
Lotus said its “safe and sound hybrid technology” simulates the traditional grunt of a combustion engine, making it “instantly recognisable that the vehicle is in motion”.
It has already put the system into a Toyota Prius, one of the most popular hybrid cars on the market. The device kicks in automatically to produce an artificial engine noise when the hybrid car runs on 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 loudspeaker positioned next to the car’s radiator, making the sound seem to originate from under the bonnet. The system produces a pitch and frequency designed to help pedestrians identify the car’s speed and distance.
Electric and hybrid cars are so quiet many fear they pose a risk to pedestrians. One US study found electric and hybrid cars moving slowly had to be 40 per cent closer to pedestrians than conventional vehicles before their location could be detected.
They have no noisy pistons, internal explosions or fan belts which cause the roar we associate with the traditional car engine. Hybrids pose an added problem. For much of the time, they are powered by a combustion engine.
But at low speeds, an electric motor takes over, making them very quiet. The new system from Lotus kicks in when sensors detect the electric motor is working.