A bunch of years ago my brother told me he read something similar about a refrigerator. I've long since forgotten the specifics, but it was something like they tweaked the operation to maximize efficiency for the specific conditions of the Energy Star test, but otherwise the efficiency was terrible. It didn't occur to me until reading this Volkswagen thing that it probably happens all the time. Engineers are good at solving problems. The solution to "pass this test" is different from "meet the conditions of this test under routine operation."Volkswagen basically adhered to the letter of the law in diesel testing, not the spirit.
And "this test" is very different from "every test." My uncle worked for Rocket Science Corporation back in the '60s and '70s. They were doing a rocket burn test on something extremely nasty - some exotic flavor of hydrazine or the like - and knew they were creating all sorts of horrific carcinogenic byproducts. What can I say - Edwards Dry Lake, and it was the '60s. EPA shows up. Announces they're going to emissions test the rocket. Everyone's eyes bug out, but it's not like they can stop. And of course, they're all in moon suits because, you know, hydrazine. And the EPA guy gets his probe ready, and they all sorta shake their heads because a fine is a fine is a fine, and they light the candle and the EPA guy goes "okay great, thanks," and drives away. He was testing for CO, and only CO. He didn't give a rat's ass that RSC was burning something so screamingly toxic that people were walking around like Homer Simpson in the reactor chamber, he just wanted to make sure the CO emissions weren't violating CO standards. Germans and Americans don't agree about what's toxic in diesel emissions. The United States only decided diesel particulate was a carcinogen like 10 years ago; Germany hasn't followed suit. Thus, I'm sure VW AG feels even more secure in their decision.