VW

The problem which VW seems to be addressing with that tricky software is - we are told  in Der Spiegel - one well recognized in the industry. Hyundai and Toyota, might be also on the same wavelength. In effect, the software picks up whether the car is in a test situation, rather than stuck in traffic, and injects urea into the converter to give a cleaner reading.

Reading up on the technology, a clean diesel engine - because diesel fuel contains more soot - will eventually produce emissions that contain nitrogen compounds. The VW models reduce the NOx emission at a cost of 10% fuel economy; contrast with a BMW where the catalytic converter injects urea to render it harmless (yes, pipi). A vehicle normally carries urea in a tank, that needs to be replenished, and that feeds into the converter. It is water-based and freezes, and needs to be heated on start-up.

These advances in diesel technology really are impressive; it all boils down to customer decisions.

Qatar is one of the big losers in the drop in value of VW stock.