Exhaust emissions standards for new cars sold in European Union (EU) states are defined by legislation adopted by the EU. They govern the limits on pollutants emitted in car exhaust gas (sulphur dioxide, nitrogen oxides, hydrocarbons, carbon monoxide, carbon dioxide and diesel exhaust particulates). The more stringent Euro 4 limits became fully effective on 1st January 2007. Euro 5 and Euro 6 limits were introduced in June 2007. New model types may now be approved to the Euro 5 standard and this will be compulsory for all new cars from January 2011. A single vehicle representative of a particular car is tested, either by independent test organisations, or by the manufacturers or importers themselves at their own test facilities. The results have to be verified by the DfT. Volkswagen is currently working on the development of cars to meet Euro 6 standards, set to take effect in 2014.
Article source: www.volkswagen.co.uk