Here I'm driving a 2012 Fisker Karma into a shop while my friend Scott shot a short video clip. The Fisker Karma is a plug-in hybrid that can run as an electric vehicle part of the time. Such silent running can pose a threat to pedestrians who don't hear it coming, and regulations to require EVs and plug-in hybrids to make some sort of noise are being drawn up.

Even though the regulation isn't final, Fisker went ahead and developed a system of their own, and they've tried to make that sound as futuristic as the car itself. Speakers at the front and back of the car produce a noise whenever the car is operating in electric mode at any speed below 25 mph.

To me it sounds like a combination of Tron lightcycle, the 2001 monolith noise, the Droid phone commercial sound, and a squadron of P-51 Mustangs banking overhead.You may not pick out the subtlety in this video because the car is entering a garage where the noise echoes around, making it sound louder than it is. That said, no one's going to miss it, and it is loud enough to be heard from inside the car at a low background level.