VW Dieselgate one year later: what have we learned about diesel cars?

Volkswagen TDI 'clean diesel' television ad screencapIt's now a year and eight days since the EPA broke the news that Volkswagen had admitted to including "defeat device" software in almost half a million so-called "clean diesel" vehicles sold in the U.S. from 2009 through 2015. That software detected when the cars were undergoing laboratory tests, and kept their emissions within legal limits during...