A survey of the number of cold vehicles on the roads

The emissions from a petrol-driven private car with a cold engine are considerably greater than that of the same vehicle with a hot engine, regardless of whether or not a catalytic convertor is installed. For this reason, the first part of the project has studied the proportion of total emissions that are due to driving with a cold engine. When all private cars are equipped with catalytic convertors, the total emissions of CO and HC will decrease to ∼ 43%, in comparison with the situation in which no vehicles are equipped with catalytic convertors. The distribution of the total emissions will be 60% and 40%, when driving with cold and hot engines, respectively. This is in spite of the fact that petrol-driven private cars only drive with cold engines for 9% of the time. In the future, one of our major tasks will be to reduce emissions resulting from driving with a cold engine. Thirty-four percent of all emissions results from journeys up to 6 km, with distributions of 27 and 7% points for cold and hot engines, respectively, when all vehicles are fitted with catalytic convertors. In the effort to limit emissions, there is therefore clear potential for replanning short journeys and using some other, less polluting, form of transport.