Electric cars are considerably quieter than their gasoline-powered counterparts, but that's not always a good thing. Pedestrians, especially those who have visual impairments, often rely on audible cues to signal an approaching vehicle. That's why a law was proposed in 2013 to add noise to electric vehicles and hybrids traveling under 18.6 miles per hour. It was supposed to go into effect in late 2015, but it was delayed. Now, it's been delayed again.