This paper discusses the development, application and implementation of FUELFAC, a computer model for the prediction of fuel consumption factors for the European vehicle fleet. FUELFAC calculates fuel consumption factors from input parameters which include vehicle speed, road type i.e. urban, rural or motorway (used for determining the length of trip associated with different driving cycles) and road geometry (e.g. slope), ambient temperature, vehicle fleet classification and signal phasing traffic flow details at road junctions (to model the different operational driving modes at signalised intersections). The model is designed to cater for different forms of available input data relating to the vehicle fleet. It can be used to calculate thermal vehicle-generated turbulence for use in turbulence sub-models within microscale dispersion models. Another application is in estimating the vehicle SO] emission rate, from which the SO: to paniculate 864 conversion can then be modelled to take into account secondary sulphate particles. Both applications are discussed in detail in this paper, with emphasis on their implementation in dispersion models for vehicle-generated particles. The results of a brief experimental programme carried out in a street in Loughborough, UK are presented.