Vehicle dynamics simulation is an essential stage of product development. It is a low cost alternative to the expensive and time-consuming experimental tests performed during the design phase. The ability to accurately predict the dynamics of vehicles can, for instance, provide useful information about their stability characteristics. Yaw instability, in particular, can cause divergent yaw behavior in conventional passenger cars and jackknife in articulated vehicles, like tractor-semitrailer combinations. These instabilities are associated with safety issues since their occurrence can cause accidents with fatal losses, injuries and property damage. Therefore, the development of vehicle models and simulation environments is necessary. This paper presents the open source package Vehicle Dynamics - Lateral. Developed using the object oriented programming paradigm, the package provides a collection of vehicle and tire models, represented by a set of base parameters and characteristic functions covering both simple and articulated vehicle simulations, as well as specific graphics generation. The package is hosted on GitHub, an online platform where software code can be shared and collaboratively developed. The goal of the package is to serve as a free, open and expandable toolbox for vehicle dynamics studies, as an academic alternative to the high cost closed commercial programs. This approach ensures thorough access to the source code and allows researchers and developers to verify all details of the implementation, as well as collaborate to the project. The code is written in MATLAB, a well-spread programming language with a significant number of adepts both in academia and industry.