US regulator missed its best chance to catch Volkswagen cheating

Chicago: More than a decade ago, the U.S. Environmental Protection Agency helped develop a technology that ultimately was used by an independent laboratory to catch Volkswagen's elaborate cheating on car emissions tests. But EPA used the technology primarily to test trucks rather than passenger cars because such heavy equipment was a much bigger polluter.

That decision meant that the U.S. regulator missed its best chance to foil the German carmaker's deception early on. The portable emissions measurement systems that EPA pioneered might have subjected VW diesel cars to on-road tests and discovered they were spewing up to 40 times the allowable levels of key pollutant nitrogen oxide under normal driving conditions. Without that test, VW was virtually home free and evaded detection for seven years.