There's a lot more to car noise than you might think. Some noises are pleasurable, some not, while some have become downright necessary for pedestrian safety. It's a subject that is now coming onto regulators' radar screens due to the potential hazards of 'silent running' with electric drive vehicles. And as Colin Peachey, a chief engineer with Lotus, tells Dave Leggett, there is also the rather ticklish issue of 'lightsaber collective consciousness' to consider when adding sound to EVs.