RAC Cars News


Diesels Breaking Legal Pollution Limits

By raccars Published

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The 'laboratory testing versus real world driving conditions' row is on the table yet again, as a new report suggests that not only do cars fail to match official manufacturer fuel economy figures when tested in the real world, but also return much lower CO2 emissions figures for the same reasons.

An investigation by the ICCT (International Council on Clean Transportation) discovered that even new diesel powered cars can produce up to 25 times the legal limit of pollution during real world testing, as opposed to when tested in laboratory conditions. On average, real world testing showed cars emitting nitrogen oxides at seven times the level set by the new Euro 6 standards, as used from September. Of the 15 cars tested, only one achieved a target of 60mg/km, with one particularly poor performance, reaching 2,000mg/km.

High nitrogen oxide levels are suspected to contribute to premature death, with the finger being pointed at diesel powered cars in the UK. Recently, Boris Johnson, the London mayor, proposed new congestion charges on diesel cars entering the capital, to combat pollution.

The tests were carried out by Emissions Analytics but the company says it is unable to release all of the data it collected. However, it did reveal that the new Citroen C4 Cactus and the Mercedes C200 tested at three times the legal pollution limit.

Real world testing conditions feature quicker, harder acceleration periods and higher speeds than laboratory tests conducted by manufacturers. These have long been criticised for stripping down cars to reduce weight beyond reasonable real world limits and for driving extremely gently, rather than as cars would usually be driven on public roads. The ICCT claims its tests showed cars breaking legal pollution limits while driving normally, rather than aggressively.

The ICCT's report suggests that while auto manufacturers are on the right path with their development of more efficient and economical technologies, these are not necessarily being applied in a way that's appropriate to real world driving conditions. Technology for selective catalytic reduction, for example, is set up to be most effective in laboratory testing conditions, rather than when driving on public roads.

Less charitably, manufacturers have in the past been criticised for paying lip service to notions of fuel economy and emissions reductions, producing vehicles that work to satisfy statistics, rather than the needs of drivers in the real world.

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