Effective numerical modelling of emission and dispersion of cars exhausted pollutants in micro and mesoscales requires use of an integrated system. The work presents the integrated computer system for modelling emission and dispersion of car exhaust pollutants in mesoscale. Whole data used in system, concerning information about topography and meteorological condition are gained from GIS. The sub model of traffic flow is based on safe distance model. In order to appropriate parametrization of maximum acceleration and deceleration of vehicles a multi-body model of vehicle dynamics has been proposed. Calculation of pollutants concentration is based on Gaussian Finite Line Source Model (GFLSM). In presented computational system all results of simulation can be visualized and export in acceptable formats to geographical information system. This causes that proposed system has almost unlimited chances in analyses of car exhaust pollutants over space and time. The author of the work deeply hopes that its results will be interesting for engineers who deal with modernization of the existing and design of new transport systems.