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Shaking the Stigma: The Demonisation of Diesel

22 May 2018


The 2015 VW ‘Dieselgate’ scandal is more than likely the reason why you’re wondering if diesel is right for you. People are worried about buying diesel cars, as they’re not sure what the future holds. However, it’s crucial to note that the problems outlined in the Dieselgate scandal only affect older diesel models.


Oxides of Nitrogen (NO & NO2) are produced as a by-product of internal combustion (in engines). These Oxides of Nitrogen – NOx gases as they are known – and related hydrocarbons and other pollutants have been linked to respiratory problems, smog and poor air quality.

Whilst diesels produce less CO2 on average than petrol engines, they produce more NOx. In modern diesels, Diesel Exhaust Fluid (DEF) – also known as AdBlue – is used within a Selective Catalytic Reduction (SCR) system to convert NOx back to Nitrogen and Oxygen. Older diesels, built before the latest EU6 emission standards were introduced, can produce much more NOx and particulates than the EU6 diesels, as they do not have this SCR technology. Since 2006 diesel vehicles are fitted with particulate filters, removing 99% of all particulates from the exhaust.

Due to the impact on public health, a number of cities in the UK have subsequently announced measures to try to reduce NOx pollution. London for example, has introduced the ‘T-Charge’, an additional fee on top of the pre-existing congestion charge to discourage older diesel vehicles from entering certain areas. This legislation will be replaced in 2019 by a more permanent Ultra Low Emission Zone. Unlike the Congestion Charge, this operates 24 hours a day, seven days a week, and it will charge drivers of non-Euro 6 diesels (and non-Euro 4 petrol cars) £12.50 on top of any other charges to enter the zone - EU6 diesel vehicles are exempt from this charge due to their low NOx emissions. Once this is up and running, other cities are expected to do the same.

Despite the recent criticism of diesel cars, The Society of Motor Manufacturers and Traders (SMMT) estimates that cars on the road only account for 14% of the nation’s NOx emissions, and that it would take four times the number of EU6 diesel cars currently on the road, to generate the same amount of NOx as one UK coal-fired power station.

Our Volkswagen & Ford diesel engines are fitted with Selective Catalytic Reduction treatment which uses the urea-based liquid AdBlue, to convert Nitrogen Dioxide into Nitrogen, Oxygen and water. This exhaust after-treatment converts up to 98% of NOx gases produced by diesel engines, meaning a significantly reduced impact on the environment.

Filtering technology fitted as standard to all of our diesels, removes up to 99% of all soot particles before they leave the exhaust. The Diesel Particulate Filter does this by extracting and storing particles until they are burnt away automatically and the filter is emptied.

Thanks to exhaust treatments such as AdBlue and diesel particulate filters, modern diesel engines are fully compliant with the latest Euro6 emissions standards. All of our EU and EEA diesel engines from September 2015 meet tough EU6 emissions regulations, meaning they are so clean they can pass freely through the Ultra Low Emission Zones that will enforce a financial penalty on drivers emitting high levels of pollutants from their vehicles.


What’s the difference between Petrol and Diesel?

Diesel cars deliver an effortless, relaxing drive because of low-speed torque. The narrow power band allows you to change up through the gears earlier and generate meaningful acceleration, making activities such as towing or carrying a large number of passengers much easier.

There has been a misconception that diesel engines are slower, noisier and more expensive to run than petrol vehicles. However engineering advancements and technologies now in-built in diesel engines, means the difference between the two is now barely identifiable.

The widely spread power band in a petrol engine typically requires higher engine speeds to deliver similar torque as a diesel, but the top-end power of a petrol offers a smooth and responsive drive which some drivers prefer.

Diesel cars are more economical than equivalent petrol models, and if you do enough miles you’ll eventually save enough money in fuel bills to recoup that extra initial cost.