Vehicle emissions vary significantly depending on the exact operating conditions. In the case of local pollutants, emissions depend greatly on the age of the vehicle and hence the emissions standards it was designed to meet. The following data are based on the vehicle emissions factors used in the National Atmospheric Emissions Inventory which are derived from Department for Transport (and other) vehicle emissions test data. The figures quoted relate to average emissions over all UK roads for the year 2005 fleet. Emissions may be significantly different for specific sections of road and will decrease for subsequent years as vehicles meeting the latest emissions standards enter the fleet.
|Vehicle type||NOx||PM 10||CO||HC||CO 2|
|Petrol Passenger Car||0.31||0.0029||1.1||0.08||186|
|Diesel Passenger Car||0.57||0.049||0.11||0.04||178|
|Diesel Light Goods Vehicle||0.87||0.14||0.46||0.10||291|
The emissions factors underlying the aforementioned data are based on testing up to the year 2001. The Department is in the process of updating these factors based on new test data accumulated over the last five years.
The aforementioned data represent vehicles at typical load conditions. The Department does not hold data on the unladen and fully laden emissions of vehicles or the relative emissions of articulated HGVs of different gross vehicle weights. However, we are conducting research on the impacts of payload on fuel consumption and hence CO2 emissions. Preliminary results from this work suggest a reduction of 0.112 miles per gallon per tonne of payload. This equates to in the region of a 1.1 per cent. increase in fuel consumption and CO2 emissions per tonne.