

Is this what a spaceship sounds like? I'd imagined something a bit more whooshy, a bit more Millennium Falcon. These stately tones are more "we come in peace" than "brace yourself for the jump into hyperspace". Still, at 25mph up Camden Road, maybe that's no bad thing.

I'm sitting in a Toyota Prius, testing out the new HALOsonic External Sound Synthesis technology, which could both save lives and liven up the morning commute no end. As electric vehicles (EVs) become part of our lives – both Nissan and Mitsubishi will have models on sale here within the next year, and charging points are being installed by local authorities around the country – one safety issue is becoming urgent. Unlike, say, an electric milk float, EVs are astonishingly silent, with just the wheel rumble and an occasional electric whine to alert you to their approach. The Royal National Institute of Blind People has been raising awareness of the risk; legislation is likely to follow soon.

All this is wonderful news for Lotus Engineering, which has been working for two years on a system to mimic engine noises. With the help of Harman International – which specialises in car sound systems – it came up with an electronic device that is wired into the engine and follows the revs to produce a synthetic engine noise.

So how does it sound? In the end Harman synthesised a number of alternatives, including a Prius in petrol-powered mode, the purring of an Aston Martin's supercharged V8, the tiger's roar of a Ferrari V12 engine, and the four-cylinder boxer engine you might find in an Alfa Romeo. And just for good measure, they added two spaceship sounds: rising and gently descending.

Tony Harberman, director of sales, lets slip the fact that these sounds were inspired by spaceships in well-known sci-fi films. As we float gently through the streets of London, a construction worker does a double take; an entire column of schoolboys, coming out of Regent's Park, nudge each other and point. Which film? It's definitely not Star Wars, I'll tell you that much.