Just when it seemed that the situation for diesel car manufacturers couldn’t get any worse, a new study has revealed that even the newest diesels are more polluting than we thought. The study calls into question why European regulators continue to favour diesel over petrol, despite vast evidence that this isn’t the best option.

More polluting

The study was conducted by Transport & Environment (T&E), an organisation based in Brussels that lobbies for sustainable transport. Its findings said that the typical diesel car emits 42.65 tonnes of carbon dioxide across its lifecycle. That’s 3.65 tonnes more than a petrol car.

T&E says that the research “debunks carmakers’ claims” that diesel cars are the best way for countries to hit their climate targets, as they are not only more polluting than petrol, but the pollutants they emit are more harmful. These include nitrogen oxides and particulate matter, as well as more CO2 than petrol cars. They also cost €2,000-3,000 more to buy. The findings call into question the usefulness of the recently announced diesel scrappage schemes, where many car manufacturers are offering discounts off new diesels for customers who trade in older models.

Declining sales

The sale of diesel cars has been in steady decline since regulators in the US uncovered the Volkswagen emissions scandal two years ago. This discovery led to much closer scrutiny of the claims made about the environmental friendliness of the diesels. It has lead to many cities considering a ban on diesel vehicles.

According to JP Morgan, the result has been a dramatic reduction in the diesel share of the market. This is on track to go from half to one-third by 2020. Carmakers still fight for diesel’s clean credentials, however, with Daimler chief executive Dieter Zetsche saying that they emit 15-20% less CO2 than equivalent petrol cars.

Different story

The research conducted by T&E seems to paint a different picture. Its study found that diesels only emit less CO2 when regulators narrowly look at the emissions from tailpipes. The study looked at the lifecycle analysis, including the production of the car, sourcing of fuel and materials for manufacturing, car usage and recycling of components.

Based on this thorough analysis, it found three reasons why diesels were more polluting:

  • Diesel fuel undergoes a more intensive refining process
  • Diesel combusts at higher temperatures, so components are heavier and more robust to handle this
  • Diesel fuel is cheaper, so drivers tend to use their vehicles more

This coincides with a report from the journal Nature, which looked at the number of deaths caused by diesel cars following the so-called Dieselgate scandal. The researchers calculated deaths in Norway, Sweden, Austria and the Netherlands. They concluded that around 10,000 deaths every year could be attributed to small particle pollution that comes from light duty diesel vehicles.

The study also found that, if diesel cars emitted the same amount of NOx as petrol equivalents, some 4,000 out of 5,000 premature deaths would have been avoided. Countries such as Italy, Germany and France see the highest number of these deaths due to their higher populations and the high number of diesel vehicles in their national fleets.

Biased regulations

T&E blamed the biased regulations and taxes present in many countries for the problems with diesel vehicles, rather than the manufacturers. For example, tax on diesel is less than on petrol. This makes it 10-40% cheaper across many European countries. Only the UK doesn’t have this tax gap. T&E called for the EU to stop pouring money into a ‘niche 20th-century technology.’ it championed a technology neutral approach, with fair fuel and vehicle taxes across the board.


Will these new findings heap further misery on the diesel vehicle industry? Are they likely to put you off buying a new diesel? Leave a comment to share your view. 

Would love your thoughts, please comment.x