Blimey, if this is true..... designing a software algorithm in cars that detect the emissions test procedure (hold at certain revs for fast idle test?? no idea how for normal idle??) and cutting emissions to pass. Presumably at the expense of performance which isn't needed during such a test.
http://www.telegraph.co.uk/finance/n...s-testing.html
http://www.bbc.co.uk/news/business-34311819