Cold Diesels Pollute More

Tens of millions of diesel-powered cars around the world are emitting more pollution - more than what the manufacturers claim - when it is cold, according to new research published in the UK this week. The research by testing company Emissions Analytics found that noxious gases in most popular diesel-fuelled vehicles are significantly higher once the mercury drops below the 18 centigrade mark.

The test was conducted with 213 models spanning a total of 31 manufacturers, with the worst result amongst the Euro 5 generation cars (2009 to 2011). The reason for the higher pollution levels is not due to the cold air ‘trapping’ the gases but because at lower temperatures, the vehicle’s pollution controls are partially or completely turned off to protect the engine; well, at least that is what the manufacturers claim.

This deliberate bit of design by the manufacturers is apparently within the European Union rules, according to the manufacturers, as long as the cut back is there to protect the engine, and of course they all claim that is why the pollution controls are reduced during cold weather. Engineers will tell you that extreme temperatures (too hot or too cold) can and will damage an engine and thus once the temperature drops below freezing, pollutants in vehicle emissions would be expected to rise. What is surprising is that the threshold in the recent test was set at 18 centigrade which some would say is far too high altogether.

The suspicion is that the threshold is set at 18 so that manufacturers can attain better fuel efficiency figures, but car manufacturers insist that this is not the case and it is a way to ensure that vehicle owners avoid large repair bills. For now though, it would appear that manufacturers and perhaps some governments knew about the higher risk in colder climes but were just not telling the public.

Manufacturers are also insisting that they are investing billions of dollars to develop increasingly clean and green engine technologies so that in the future there will be a significant lowering of emissions, particularly when there is a chill in the air. Our sponsor over at X-1R is quick to point out that its new Diesel Treatment is proven to reduce particulate emissions by an average of 65% at idle and improve fuel efficiency by 8%; perhaps some manufacturers would care to investigate using the X-1R product range, just perhaps.