The most dangerous three-word phrase in business is: “Everyone does it.”

However conventional it is to bend the industry’s regulations, however great an advantage your rivals gain, however much pressure you face to do so too, there is a simple test for deciding whether to succumb to temptation. What would happen if the world found out? How great would the damage be?

Volkswagen’s installation of software to make its diesel cars emit more pollution on the road than in official tests is a disaster that has forced the resignation of Martin Winterkorn, chief executive. It could tarnish the entire European auto industry, which has invested heavily in diesel technology. But it is hardly the first time that a vehicle manufacturer has behaved sneakily.