German watchdogs combing through carmakers' technology to uncover emissions test cheating software have discovered that automobile manufacturers are using other methods that lead to lower emission counts. These revelations from German Transport Minister, Alexander Dobrindt. Allegedly, the carmakers "tweak engine performance" which results in more emissions but less data on those emissions when the software is checked. 

According to Reuters, Germany's KBA Federal Motor Transport Authority tested 53 vehicles to find out if carmakers followed the same practices that Volkswagen did, in order to manipulate emissions testing. The results of the tests found that VW was the only manufacturer that made use of cheating software, but, the other manufacturers dabbled in what is being called a 'thermal window'. 

EIT Stock ImageDue to the 'thermal windows' findings, the German government is set to recall 630,000 vehicles. Government officials talking to the media said: "The recall is aimed to ensure that a legal loophole allowing manufacturers to throttle back emissions treatment systems under certain circumstances is tightened to make sure lower levels of pollution going forward." 

The 'thermal window' approach - most probably coaxed up by very clever automotive engineers - reportedly works around the process of condensation build up in catalytic converters and the throttling back emission management systems to protect the engine from that build up. 

Switching off or throttling back emissions treatment systems, however, has the added benefit of improving engine performance and stretching the interval between refilling vehicles with urea, a subtance needed to extract NOx from exhaust fumes

- Markus Wacket, Reuters News Agency

The German government is trying to cut down on the amount of nitrogen oxide (NOx) that is polluting the air and that is part and parcel as to why they are recalling 630,000 vehicles so that this work-around 'thermal window' solution can be investigated.