Following last year’s Volkswagen emissions scandal (I say ‘last year’s, but VW’s woes are very far from over…), the British Government tested the 37 best-selling diesel cars in the UK – and found that not a single one of them could meet the official emissions figure for nitrogen oxides (NOX).
One car, the Vauxhall Insignia, emitted more than ten times the Euro 5 legal limit of 180mg/km when it was tested under real world driving conditions, while even the newest Euro 6 compliant cars were guilty of emitting more than six times the lower limit of 80mg/km.
German tests, which subjected 56 vehicles to independent scrutiny, showed similar results.
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If you are surprised by any of this could you please raise your hands? What, no one? I thought not; we are so used to hearing that cars use more fuel and create more exhaust emissions than the official figures would lead us to believe that we are almost inured to it all.
But should we be? And what lies at the heart of the problem? Let me see if I can explain.
The EU test cycle
All cars sold within the European Union are subject to a standardized test cycle, in which they have their fuel consumption and exhaust emissions monitored to try and set a benchmark figure by which all cars can be compared.
The New European Driving Cycle (NEDC) as it’s known, is a noble objective but, as in every sphere of business and competition, rules are there to be bent and twisted until they almost snap and few are better at this than car manufacturers.
Volkswagen managed to engineer its cars to detect when they were being tested, at which point they went into a special test cycle that was unrepresentative of real world running.
Other manufacturers employed different techniques to massage the results, including gear ratios and change-up points on cars with automatic gearboxes that have been specifically calculated to favour the testing cycle (why do you think your car has a ‘sport’ setting on the gearbox?).
Some, including Mercedes-Benz and Opel are voluntarily recalling vehicles so that they can change the software that governs NOX emissions, while Alexander Dobrindt, the German transport minister claims that his government has detected “irregularities” in cars from at least 11 other manufacturers.
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The solution is something called the Real Driving Emissions (RDE) test, which are due to be implemented for all vehicles sold in the EU from 2017 onwards.
The new testing cycle is expected to give results that more closely mirror those found under real world conditions, and should reflect more accurately the sort of results that owners themselves can expect to encounter.
In the meantime
In the meantime, VW has agreed to buy back half-a-million cars in the United States of America, and has set aside £12.6billion to meet the costs – including fines – that it expects to face. It has also said that it will “fix” those cars that are affected in other countries, although not all owners are expected to sign up to the process as the fix may well lead to higher running costs by way of increased fuel consumption.
Other manufacturers are currently looking at their own procedures and I predict that others will be forced to hold their hands up and admit to irregularities in their processes.
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What can I do?
For consumers, the answer is to judge all advertising claims, including exhaust emissions and fuel consumption data, with caution. What Car? and Honest John feature crowd-sourced fuel-consumption figures that are likely to predict the sort of fuel consumption that you can expect with a high degree of accuracy.
It’s also fun to see which manufacturers achieve the highest percentage rating, which might give you the odd hint as to who plays the game the best, something you might like to take into account when you next change cars. (Although VW says that it sold more cars in the first three months of 2016 than it did over the same period last year, which must prove something...)
Or, you could just avoid buying a diesel car. The exhaust emissions are carcinogenic and contribute to the formation of health-damaging smog. As a result, diesel kills millions worldwide every year. The financial benefits aren’t as clear-cut as you might imagine, either. If you drive fewer than 12,000 miles a year, then you’ll probably be better off buying a petrol car anyway.
For more tips and useful information, browse our motoring articles.