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 StandardDateCarbon MonoxideNOXPM
Euro 1July 19922.72-0.14
Euro 2January 19961.0-0.08
Euro 3January 20000.640.5000.05
Euro 4January 20050.50.2500.025
Euro 5September 20090.50.1800.005
Euro 6September 20140.50.0800.005

Euro Emissions Standards For Petrol Cars

Euro StandardDateCarbon MonoxideNOXPM
Euro 1July 19922.72--
Euro 2January 19962.2--
Euro 3January 20002.30.15-
Euro 4January 20051.00.08-
Euro 5September 20091.00.0600.005
Euro 6September 20141.00.0600.005

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.

What do we think?

It's still the case that diesel cars are generally more suited for individuals doing high mileage, due to the increased initial purchase cost, and higher price of diesel fuel vs. petrol. Diesel engines are more efficient and offer better MPG (miles per gallon) compared to a petrol engine, so for individuals travelling a lot of miles the savings eventually outweigh the costs.


In the short term however with Euro 6 standards resulting in improvements in the fuel economy and emissions of new cars, a diesel is certainly worth consideration especially with the savings which are currently on offer.

The brand new Suzuki S-Cross now has a massive £3,750 discount available (£2,750 for non-Suzuki owners) on diesel models.

Or how about the Nissan Pulsar with a £2,750 deposit contribution available with Nissan's 3.99% APR representative PCP finance (or a £1,000 deposit contribution when taken with 0% APR finance).

There's also fantastic deals available on the Suzuki Vitara, Nissan Micra, Nissan Juke, Nissan Qashqai, Nissan X-Trail, Nissan Navara, Subaru Forester, Subaru Outback & Subaru XV. T&C's apply.