Stop, look and listen – it’s a familiar road safety message. But what if you can’t hear a car approaching? What if the car is an electric or hybrid vehicle that makes almost no sound? The number of electric and hybrid cars on our roads is rising: sales were up almost fourfold in 2014 to 14,498, according to the Society of Motor Manufacturers and Traders. We’ve all been encouraged to go green by plug-in grants towards the purchase price of cars such as the Nissan Leaf and the Toyota Prius. And if your car has zero emissions, you’ll pay zero vehicle excise duty.