The use of model-based software development in automotive applications has increased in recent years. Current vehicles contain millions of lines of code, and millions of dollars are spent each year fixing software issues. Most new features are software controlled and many times include distributed functionality, resulting in increased vehicle software content and accelerated complexity. To handle rapid change, OEMs and suppliers must work together to accelerate software development and testing. As development processes adapt to meet this challenge, model-based design can provide a solution.Model-based design is a broad development approach that is applied to a variety of applications in various industries. This paper reviews a project using the MATLAB/Simulink/Stateflow environment to complete a functional model of a low cost radio. We approached the project independent of any specific software architecture, using only written specifications and current working units as a guide to functionality. The final result is a model that captures the functional behavior of the radio. While the model could be used for auto code-generation, this project focused on utilizing the radio model to prove-out the functional and HMI specifications.A discussion of our design approach, including architecture, testing, related HMI components, and lessons learned, are included in the paper.