[GH85Carrera]

The fallout from the Volkswagen diesel scandal is spreading fast to the company's other famous brands, including Porsche and Audi, and across the Atlantic to the U.S. The scandal reached down into the company's engineering corps as the CEO of Volkswagen's US business, the research and development chief from Audi and the engine chief from Porsche, which are part of the Volkswagen Group, are said to be following Volkswagen's CEO out the door of the company, according to multiple reports Thursday. The impending departures are a sign that the Volkswagen scandal is ready to grow to much larger proportions.

and how it can be done

Normally it is a case of pointing the finger down the food chain until someone cannot point any further.
Engineers are normally the Middle Class people, They don't have the money for a prolonged out of work. So there is only so much risk they would take at their job. It would be nice that everyone would be brave enough to stand up and say "This is wrong, I won't do it!" however with the risk of getting fired, plenty of the power is still in the higher ups.
Also it is quite possible that the engineers could design something without full realization on what they are doing.
I need you to code a function when variables are between this range, that returns a value in this range.
The function is created.
Then it will go to an other engineer, We have the function to optimize fuel efficiency in place, could you add this function to your code.
The function is added.
The higher ups can organize their orders so the engineers doesn't have the full picture of the scope. However when things goes down they will see in the comment that engineer who had made the function and the other who added it. They get canned, for doing their work, and never had an inkling on what they were doing on the grand scheme of things.

and how it was found
Sales of Volkswagen diesels have been on the rise in the US in the last few years, despite this more stringent regulation. ‘Clean diesel’ is a goal for the industry, and a European non-profit, the International Council for Clean Transportation, got in touch with researchers at the Center for Alternative Fuels and Engine Emissions (CAFEE) at West Virginia University. The question of how Volkswagen was able to produce a diesel engine in compliance with US regulations was high on the list of priorities, and the team was well-equipped to test Passats, Jettas, and Golfs in real-world conditions.
Despite passing emissions tests required by the US government, CAFEE found these engines were out of compliance. This apparent discontinuity can be brought to light by examining how diesel emissions are measured. An EPA notice of violation explains this was done by a bit of code functioning as a ‘defeat device’ that would sense when the vehicle was under test. Software installed in the electronic control module (ECM) would detect when the car was undergoing emissions testing by reading, “various inputs including the position of the steering wheel, vehicle speed, the duration of the engine’s operation, and barometric pressure.” Under these conditions, the ECM would use a different ‘map’ that would reduce torque and NOx emissions. Under normal conditions – when the vehicle was not being tested for emissions – a separate ‘map’ would be used that would increase acceleration, torque, or fuel economy. CAFEE was able to determine this because of a portable testing rig; instead of testing emissions in a garage on a dynamometer, the researchers performed their tests in real-world conditions, driving around Los Angeles, from LA to Mount Baldy, and from LA to San Diego.