Analysis of systems containing both discrete and continuous dynamics, hybrid systems, is a difficult issue. Most problems have been shown to be undecidable in general, and decidability holds only for few classes where the dynamics are restricted and/or the dimension is low. In this paper we present some theoretical results concerning the decidability of the reachability problem for a class of planar hybrid systems called Generalized Polygonal Hybrid Systems (GSPDI). These new results provide means to optimize a previous reachability algorithm, making the implementation feasible. We also discuss the implementation of the algorithm into the tool GSPeeDI. Categories and Subject Descriptors I.6.4 [Simulation and Modeling]: Model Validation and Analysis General Terms Verification of hybrid systems Keywords Hybrid systems, reachability, differential inclusions