Natural Law v Governmental Law
Much as I deplore Volkswagen's actions, My sympathies lie mostly with the car maker. Governmental Laws are often arbitrary and run counter to reality. The Emission Laws are one such. As part of my technical education, I did Heat Engines. What I learnt there was that to attain higher thermal efficiencies, you had to go to higher pressures and temperatures. Chemistry tells you that all molecular activity and chemical processes are easier at high temperature and pressure. So VW are in a cleft stick situation. They are required (by Law) to attain results that fail in either one case or the other, and cannot pass in both So they came over with tests that covered one set of conditions and hid the other. It has oft been said that human laws are always broken, and indeed are made to be broken, and that Natural Laws cannot be broken, ever.