Volkswagen Scandal: Why Is It So Hard to Make Clean Diesel Cars?

Live ScienceVolkswagen Scandal: Why Is It So Hard to Make Clean Diesel Cars?Live ScienceThe company is recalling 500,000 diesel cars in the United States and 11 million vehicles worldwide because they may emit up to 40 times the allowable levels of air pollutants that are called nitrogen oxides (NOx), The New York Times reported. The ...and more »