By applying DAF SCR technology in combination with a passive soot filter, the amount of particles will be reduced, enabling EEV engines to produce even lower emissions than gas engines.

In the late 90s, the EEV (Enhanced Environmentally-friendly Vehicles) emission standard was set to promote development of cleaner engines. It was initially assumed that this standard could only be achieved with gas engines.

But technological development by DAF combined with installation of an intelligent injection and combustion system, means their diesel engines are able to achieve the low Euro 5 emission values for particulate matter without the need for a soot filter.

With this, they are now close to achieving the EEV values. Fitting an additional soot filter will result in values even lower than these.

Although the Euro 5 emission requirement does not come into force until 2009, DAF already offers a broad range of diesel engines which meet the corresponding emission values. When compared to the Euro 1 standard of around 15 years ago, these engines emit around 75% less nitrogen oxides and 94% fewer particles.

Up to Euro 3, internal engine changes have always been sufficient to comply with the new emission standards; for compliance with Euro 4 and Euro 5, exhaust gas after treatment systems are needed. Like most European truck engine manufacturers, DAF has opted for the SCR technology.

With this, AdBlue is injected into the exhaust gases, so that nitrogen oxides are broken down in the DeNOx catalytic converter into the harmless substances nitrogen and water. SCR technology is relatively simple and thus reliable and efficient, say DAF.

As this emission after treatment technology does not interfere with the engine, the engine settings can be optimised to achieve ideal combustion, resulting in low fuel consumption.

The introduction of DAF SCR technology coincides with the launch of a completely new series of Paccar engines that use an advanced high-pressure fuel-injection system for the highest possible efficiency and the lowest possible emission of particulate matter.

None of the new Paccar engines needs a soot filter to meet the stringent requirement of 0.03 grams per kW/hour (ETC).

By fitting a passive soot filter, a further 50% reduction of particulate emissions can be achieved, resulting in a mere 0.015 grams/kWh. That is 25% lower than the EEV standard!

The 9.2 litre Paccar EEV engine emits 2 grams NOx, 0.05 grams CO, 0.1 grams hydrocarbons per kW/h, and an almost negligible emission of visible smoke. Until recently, it was assumed that these values could only be achieved with gas engines, and indeed, they come close to 'zero emission,' say DAF.

At the beginning of next year, or earlier if technically possible, the Paccar 9.2 litre EEV engine, which has an output range from 250 to 360hp, will become available for use in buses. Later in 2007, it will also become available for trucks. An EEV version of the 12.9 litre Paccar MX engine will also become available, with outputs ranging from 360 to 510hp. This will likewise be fitted with a passive soot filter.

As well as the Paccar PR EEV and the Paccar MX EEV engines which have low emission levels, DAF will start supplying passive soot filters from the beginning of next year to be used on existing buses and trucks fitted with Euro 3 engines. These filters can reduce the emission of particulate matter by around 50%. With retrofit soot filters, DAF is able to cater for transport operators who are faced with local legislation requiring the presence of a soot filter in built-up areas.