High diesel NOx emissions prevail

A study by Dutch consultancy TNO has found that in spite of facing a tighter NOx emissions limit of 80 mg/km, diesel-driven Euro 6 vehicles emitted around 500 mg/km in real-world driving circumstances, which means they are approximately equal to Euro 4 and Euro 5 vehicles. The new Euro 6 standard was introduced at the start of 2014.

Part of the reason for the huge difference between a car’s performance in the real world and in a type approval test is that these tests are obsolete, so that carmakers are able to circumvent the rules. A new system of better real-world emissions tests was due to be introduced in 2012 but has been delayed through industry lobbying and arguments intended to weaken the new rules. 

“The delays to real-world driving emissions tests are contributing to hundreds of thousands of needless deaths. The weakening of proposed new test procedures casts significant doubt on whether the new system will ever be effective. Cities have no choice but to ban diesels and restrict vehicle access until tests can effectively distinguish between clean and polluting vehicles,” said Greg Archer of T&E.

Sales of diesel cars have grown strongly in Europe from around one-third of new cars in 2000 to over half today. This is largely the result of generous tax breaks for diesel cars.

Source: T&E News, 1 August 2014. 

TNO report: “Investigations and real world emission performance of Euro 6 light-duty vehicles.” TNO 2013 R11891. 

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