Kinematics and dynamics constraints of mobile robots can be modeled by means of differential equations. Simulation and sampling based path-planning algorithms need a model of these constraints in order to deal with non-holonomic mobile robots. Usually these models are hard-coded in the implementation of those algorithms and this makes hard their reuse. In order to design these algorithms in a modular and extensible way we have to explicitly represent the models of the robots and decouple them from algorithms implementation. We propose DCML, a Domain Specific Language that can be used in order to describe differential models, and a tool that allows developers to automatically generate the code that implements the model. We also aim to show how this Model- Driven Engineering technique can be used with good results. As a demonstration of what can be done by means of our DSL, we present the differential model of an omnidirectional holonomic robot called BART, and we show how this model can be integrated in a framework for path planning.