You'll have no doubt seen the term 'Euro 6' more and more over the last few years. You'll also have seen articles explaining how it will affect you as a driver, or what its benefits are. But what is it, and what does it mean?
Euro 6 compliant diesel engines
Euro 6 is the latest diesel engine emission legislation being enforced by the European Commission. The original legislation - Euro 1 - was introduced way back in 1993. Over twenty years later we've reached the sixth iteration of this legislation, which is designed to regulate the level of pollutants emitted from diesel engines.
The European Commission identified two substances contained within the exhaust system - Oxides of Nitrogen (or NOx) and Particulate Matter (basically soot particle) - as harmful, therefore needing to be controlled and reduced.
So, the last few decades have seen engine manufacturers invest heavily in developing and implementing new technology. This has resulted in a dramatic fall in the levels of NOx and Particulate Matter being emitted from the exhausts of new diesel engines, as well as an improvement in air quality.
In fact, manufacturers have embraced the legislation to such a degree that the air coming out from the exhaust of a Euro 6 diesel engine is cleaner than ever. What's impressive about this is that permitted levels of NOx for Euro 6 engines have been reduced by 75% compared to the current Euro 5 standard. The reduction in Particulate Matter is around 99%.
The Euro 6 regulations in full
All NOx emissions reduced to 0.46 grams-per-kilowatt-hour (g/KWh)
Particulate Matter reduced to 0.01gm/KWh
The introduction of a lower ammonia emission limit - ammonia being a by-product of the selective catalytic reduction (SCR) exhaust after-treatment process
The inclusion of a crank-case emission limit if a closed system is not used
An enhanced emissions durability requirement for all Euro 6 engines of up to 700,000 km or seven years for the largest vehicles
Further improvements to the engine's On-Board-Diagnostic (OBD) system performance
The adoption of new, world-wide 'transient' and 'steady-state' test cycles including cold-start and normal-running temperature components which are designed to more closely reflect what a vehicle does in real-life
With the introduction of the Euro 6 regulation this is the first time a 'World Harmonised Test Cycle' has been used for engine certification