Abstract
Keywords: cold-start emissions, passenger cars, petrol, diesel.
Latest development of engines and emission control devices in passenger cars to bring them in compliance with the last amendments of European directives for exhaust emissions (EU3 and EU4) has apparently improved also their performance with regard to cold-start related emissions, even if the targeted test procedure to specifically measure and control these emissions was included in the type approval requirements of new types as late as year 2002.
The test results presented in this paper demonstrate that cold-start performance has been gradually improved, and emission rates measured at low ambient temperatures (-7 ºC) have declined. However, the negative effect of cold environment with regard to fuel consumption and CO2 emissions has not much diminished. According the results, elevated emission levels at cold-start are also mostly associated with petrol-fuelled cars, as much lower levels were recorded for those with diesel engines.