Debunking some myths surrounding diesel cars

Vehicle emissions are a key talking point when it comes to environmental pollution. In the past, car makers used to produce cars that delivered greater and greater performance without much regard for the pollutants coming from the exhaust. However, with studies proving that greenhouse gases are affecting the environment, governments and legislative bodies across the world have clamped down on vehicle emissions.

Since September 2014, all new cars registered are required to meet Euro-6 standards. This European Union legislation aims to make cars environmentally cleaner by reducing the levels of harmful vehicle emissions such as nitrogen oxide (NOx), carbon monoxide (CO), hydrocarbons (THC and NMHC) and particulate matter (PM, which is basically soot from diesel engines). The upside of reducing these pollutants is that it becomes cheaper to run your car, thanks to improved fuel economy and reduced car tax.

Older diesel cars that produce higher levels of NOx and particulate matter are starting to come under fire from a number of environmental groups, as they've previously been subject to lower road tax and company car tax, due to their lower CO2 emissions, but in spite of their higher NOx and PM emissions. This is no longer the case with Euro 6 diesel engines, which are subject to more stringent rules than their older counterparts. The permitted level of NOx emissions has been dramatically dropped to a maximum of 80mg/km, compared to 180mg/km for Euro 5 diesel cars.

Euro emissions standards for diesel cars

Euro standard Date Carbon Monoxide NOx PM
Euro 1 July 1992 2.72 - 0.14
Euro 2 January 1996 1.0 - 0.08
Euro 3 January 2000 0.64 0.500 0.05
Euro 4 January 2005 0.5 0.250 0.025
Euro 5 September 2009 0.5 0.180 0.005
Euro 6 September 2014 0.5 0.080 0.005

Euro emissions standards for petrol cars

Euro standard Date Carbon Monoxide NOx PM
Euro 1 July 1992 2.72 - -
Euro 2 January 1996 2.2 - -
Euro 3 January 2000 2.3 0.15 -
Euro 4 January 2005 1.0 0.08 -
Euro 5 September 2009 1.0 0.060 0.005
Euro 6 September 2014 1.0 0.060 0.005

There are several benefits of a Euro 6 diesel engine:

  • Increased Efficiency - As manufacturers have to make sure engines are as efficient as possible to meet the Euro 6 standards, they provide the added bonus of reducing your fuel costs by producing increasingly fuel efficient engines.  On average a diesel engine will have up to 30% better fuel economy compared to a similar petrol engine.
  • Reduced CO2 - On average, a diesel engine will produce up to 25% less CO2 than its petrol sibling, in turn reducing your carbon footprint. Road tax is calculated by CO2 emissions, so a diesel engine can be more cost effective.
  • Future Proofing – The future of older diesel engines is unclear but is likely to include extra costs to discourage use. However, by driving a vehicle that adheres to Euro 6 standards now, you may avoid any extra costs in the future.