EMISSIONS

Despite being a great liberator, the motorcar is also a serial polluter. Whether powered by internal combustion (ICE), or electric, the automobile has a negative environmental impact. As the majority of cars on our roads are ICE-powered, this article focuses on petrol and diesel tailpipe emissions of production cars, while providing an overview of the latest developments.

What do engines burn?

While ICEs can combust alternative fuels, petrol and diesel are a complex mix of chemicals, originating from not only crude oil but also bio-fuels. British diesel may contain up to 7% bio-diesel (hence the B7 pump labelling), while petrol can contain up to 5% bio-ethanol (E5), a percentage mooted to double at some point within the next twelve months. Added to this base fuel are additive packs, which differ between individual fuel brands. While you can conclude that the ‘base’ fuel is the same, regardless of the filling station, extra additive packs influence the combustion characteristics and, therefore, the resultant emissions. In the UK, fuel is supplied in both winter and summer grades, yet it is worth noting that petrol, especially, deteriorates if left for more than a few weeks. For these reasons (and more) the chemistry behind road fuels is immensely intricate.

The legislative situation

As governments realised the undesirable link between exhaust emissions and poor air quality, they drew-up statutory limits. While we do not intend to provide detailed legal analysis, knowledgeable DIYers must be aware of the situation, whether maintaining, repairing, or even modifying their cars. For specific legal advice, however, we advise that you consult a solicitor.

As an overview of today’s state of affairs in the UK, there are two main sources of legislation and two means of enforcement. The main one involves Whole Vehicle Type Approval, which assesses new car models, governed in Europe by the UNECE. The UK joined this organisation before the EEC, the forerunner to the European Union (EU). Therefore, the rules will continue post-Brexit.

Whole Vehicle Type Approval harmonises technical criteria between nations, including environmental standards. Besides, it classifies types of vehicle, which answers questions such as what distinguishes a motorcar from a quadricycle? The rules are incredibly detailed and all new car models must follow them so they can be sold. These include the limits that a model range must attain to achieve the relevant EURO