September 2015 will see all new petrol- and diesel-engine vehicles weighing over 3.5 tonnes having to meet strict emissions guidelines known as Euro 6.
The aim of Euro 6 is to reduce the amount of harmful exhaust gasses emitted by vehicles, such as nitrogen oxide (NOx), carbon monoxide (CO) and particulate matter (PM).
The focus of Euro 6 is predominantly on the emissions of diesel engines, requiring a reduction in NOx levels of 67% compared to Euro 5. Euro 6 also brings the standards for petrol and diesel engines closer together. Whilst the levels for CO and PM have remained the same for both petrol and diesel cars, the NOx levels for diesels have dropped from 0.18 g/km to 0.08 g/km. NOx levels for petrol engines stay at 0.06 g/km.
NOx is formed whenever high-temperature combustion occurs in the presence of nitrogen and oxygen, such as in a combustion engine, power station boiler or a lightning flash.
These gasses contribute to a variety of factors, such as acid rain, smog, global warming. They can cause serious respiratory problems and can worsen some conditions such as emphysema and bronchitis and aggravate heart disease.
As NOx gasses can be transported over long distances, using a containment system such as London’s low-emission zone simply will not work to improve air quality to target levels, and greater steps need to be taken.
Changes to Diesel Engines to Meet Euro 6
Reducing NOx emissions from diesel engines is achieved through three main technologies: Selective Catalytic Reduction (SCR), Exhaust Gas Recirculation (ERG) and Diesel Particulate Filter (DPF).
The previous Euro 5 standard could be met by choosing just one of the available technologies. However, in order to be Euro 6-compliant, a combination of all three is required.
The most visible change to the driver is through the SCR system with the addition of AdBlue. AdBlue is liquid containing ammonia which is added to the exhaust system and reduces the levels of NOx emitted.
Euro 6 and Car Buyers
The new legislation does not directly affect car buyers, but it is worth being aware of it. As this does not affect existing diesel vehicles, it should not been seen as an excuse for manufacturers to sell more vehicles.
New Euro 6 engine car deals have been available for some time, with Mercedes leading the way.
Diesel-engine cars have always been more expensive to purchase than petrol models due to their fuel efficiency and longevity, and it could be that Euro 6-compliant engines further open this gap as manufacturers try and recoup some of the investment that they have made.
Despite this, buying a Euro 6-compliant vehicle means that you are purchasing the very latest technology and with it the decreased fuel consumption and lower road tax, both of which will save the buyer money.
This does all sound like doom and gloom for the old diesel engine, and as emission levels become lower, road tax costs are likely to rise even further.