FOR THE past 20 years Australian vehicle-emissions standards have taken their lead from the United Nations Economic Commission for Europe. The latest of these adopted here, the so-called Euro 5, came into effect locally for all new-design ‘Light Petrol and Diesel’ vehicles in November 2013 and for existing designs of the same vehicles from November 2016. Light vehicles are anything less than 3.5 tonne GVM, so pretty much everything that’s a recreational 4x4. The main impact of Euro 5 over the previous Euro 4 standard was in the tightening up of the allowable soot (particulate) emission of diesels, a problem addressed via the introduction of diesel particulate filters. Euro 6, already in play in Europe and soon to be introduced here, calls for a reduction in the output of the various oxides of nitrogen, collectively known as NOX, and brings Selective Catalytic Reduction (SCR) technology, also known as Adblue. Some locally delivered 4x4s, such as the Ford Everest, already have SCR and meet Euro 6.