Hybrid vehicles have the potential to save a few bucks at the pump, but advocates for the blind have continued to warn about their potential to harm to the seeing impaired. Lotus' automotive consultancy arm is trying to avert the risk of hybrids quietly running in electric mode with its 'Safe and Sound' demo car.

This specially equipped Toyota Prius has been fitted a waterproof speaker mounted above the radiator that can emit a sound similar to a flat-six or V8, based off the vehicle's speed and throttle position. Once the internal combustion engine kicks in, the system is muted, allowing the 1.5-liter inline four to sing its siren song.

Hit the jump to read the press release and see a video of the 'Safe and Sound' demo car in action. Also keep in mind that we've yet to run across a report of a blind person being hit by a hybrid car, though there was that one kid who got knocked off his bike.