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Are Diesel vehicles really that bad?

So as you will most likely know EU and the UK officials have recently started to turn against Diesel powered cars a fuel type they have supported for years due to its lower CO2 emissions and better fuel economy. Now they are suggesting such acts as banning diesel cars from some city centres and in London charging some diesels drivers with older, less Eco friendly cars an additional emission fee. Talk about scrappage schemes for owners of diesel cars are also in play and it seems like the funeral bells are pealing frantically for the diesel car.


The question is why? Why the sudden U turn from tax breaks and lower cost fuel? Well in simple terms there is a lot of worry that although diesels produces less CO2 then petrol cars on average, they can produce more of a gas called Nitrogen oxides or NOx. Now with NOx being linked to some serious health issues, such as respiratory issues, it seems like there may be some cause for concern, but I can’t help but feel that this may be a bit blown out of proportion.

All the trouble seems to have stemmed from a paper presented by Dr. Eckard Helmers of the environment campus of Trier University of Applied Sciences, Germany (Link at the bottom), after he declared that the emissions of Diesels cars is underestimated and that cars produced before 2005 could be producing much larger quantity of emissions both in CO2 and NOx then we previously thought, now having read this paper over and over, I can spot a glaring issue, nowhere can I find a study carried out on petrol cars that are pre-2005 for the same emissions. So whilst the Doctor blasts old diesels as being a lot less Eco friendly then we thought, he seems to completely forget to check if petrol cars are just as bad. Another issue I have is his claim that due to these higher emissions of older cars since the 1990’s diesel has actually been producing more CO2 then petrol cars all these years. I would like to point out that a car that has been on the road and used for over 10 years of its life is very rarely going to burn fuel and emit emissions as effectively as it did when new, regardless of fuel type. Therefore, the figures he is quoting would have been vastly different than when the car was first produced.

The Doctor then quotes the average rate of CO2 emission per car in Japan is 20g of CO2 less then it is in Europe which he credits to the very low amount of diesel cars and the very high amount of hybrid cars, suggesting that the benefits of a diesel I.e. lower CO2 emissions can be solved by more hybrids. The issue is that hybrids may look great on paper, but in reality the cars are rarely as efficient as they claim to be because the catalytic converter seldom reaches optimum temperature due to the petrol engines sporadic use. Yes you may be producing less CO2, but with a less effective catalytic converter a lot of what you’re putting out the back could be carbon monoxide and other nasty pollutants, which are going to do a lot more harm the CO2.

The Doctor conceded that newer diesel cars with particle filters fitted are a vast improvement on older models, but quotes that of around 350 (post-2005) diesel taxis tested, 9% of them had malfunctions with the particle filter causing more pollution. Now a taxi is one of the most used cars there is. They are used every day continually so if a car subjected to that much use produces such low numbers of faults, I can imagine it’s even lower for normal people’s cars. And again no test is conducted to see how many fuel efficiency faults are in petrol cars.

Of course we can’t get away from the fact that diesel cars can produce more NOx then petrol’s do, but in the same breathe we have to point out that petrol’s still produce more CO2, and the fact is that to much of either one is bad news for us and the planet. We also have to think about all the other by products of the combustion engine and not keep focusing in on just one or two.

It all comes down to this, are diesel cars as bad as they are currently being branded? The answer is no. Are they saints?, Again, the answer is no. However I wouldn’t call any of the alternatives saints either so until something better comes along I feel the diesel car is here to stay.

About Mark Lean

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