A car-following and lane-changing microsimulation model of a two-lane road section has been written in SLX (Simulation Language with eXtensibility) as part of an extensive research project by the University of Rome Transport Department to qualify and quantify the environmental impact of traffic. The microsimulation model is part of a three-step approach, involving a traditional transport macroscopic model, the microscopic model, and an ultra-micro model. The microsimulation model's car-following and lanechanging rules are presented and described in detail, and model outputs are commented. The paper includes a short description of the Microsoft Visual Basic user-interface developed by the author and the animation performed by means of Proof Animation.