What if the VW engineers that designed this are right and the regulators are wrong? They designed an engine to provide optimal fuel efficiency across the duty cycle of the engine. This would result in fewer emissions and less overall damage to the environment than an engine designed to reduce NOx emissions to a minimum. Perhaps the solution would be the engine with the programming designed by the engineers but GPS so that in urban environments, where NOx is a serious problem the engine would operate at lower efficiency but at minimal possible NOx emissions but on the open road, where total emissions are a concern the engine would operate at peak fuel efficiency. Perhaps the regulatory process is the problem that engineering concerns are not adequately accounted for. The engineer, understanding the impact of his technology on the environment would choose to optimize for peak fuel economy yet meet the government imposed standard when necessary. If it is necessary to minimize NOx in central London, do so. The VW engine can do this.