Remember that episode of The Office when Andy uses his Prius as a stealth ramming device and lodges Dwight into some bushes? Japan, the land of everything mystical and wonderful, must have seen that episode too and has some issues with the quiet demeanor of hybrids. They are the best selling vehicles over there and citizens have expressed concern to the Transportation Ministry that they might be too quiet. A dream team panel comprised of scholars, consumers, police, and blind people decided the best way to deal with this problem is to make the cars louder when running on batteries.
This is in the very preliminary rounds and a specific sound hasn’t been chosen, nor how to make it pedestrian-friendly while not a nuisances to everyone else. The panel is expected to wrap up everything by the end of the year.
GM has tackled this issue already in the upcoming Chevy Volt. We found out about it when we test drove an engineering mule a few months back. The driver activates the sound which is a lot more friendly than blowing the horn. This is a larger issue for the Volt than traditional hybrids who generally run on the combustion engine a lot sooner than the Volt’s generator kicks in. The Volt is totally silent for about 40 miles of travel.