Can a Car Run Too Quietly?

The Prius is so quiet that Toyota is planning to offer an audio system that makes typical engine noises. This is in response to safety complaints that have arisen because pedestrians cannot hear the car coming. Using the device would be voluntary, and it can be turned off with a switch, but it will automatically turn on every time the car is turned on. The audio device hit the Japanese market in August of 2010, and Toyota will decide whether to offer it in the United States.

More facts about alternative cars:

• It would take 20 new cars to put out the same amount of emissions that most cars made in the 1960s.


• The first electric car was invented in 1839 by Scotsman Robert Anderson, and hybrid cars were first shown at a Paris salon in 1899.


• The search for a reliable alternative fuel has been going on for as long as cars have been on the market. Some alternative power sources that haven't made it big are wood, compressed air and human "pedal power" — Fred Flintstone-style.