The Software That Knew When to Behave
The elegant simplicity of the fraud was what made it so devastating. When a Volkswagen diesel engine detected the telltale signs of laboratory testing—stationary wheels, controlled temperature, predictable throttle patterns—software buried deep in its electronic control unit would shift the vehicle into a special mode. Emissions controls that remained dormant during normal driving would spring to life. Nitrogen oxide output would plummet to legal limits. The test would pass. Then, back on actual roads with actual drivers, the software would return the engine to its default state: powerful, efficient, and releasing nitrogen oxides at levels up to 40 times the legal threshold .