The design of complex real time embedded systems such as Brake by Wire is becoming increasingly difficult as more and more functionality is added. A technique is required whereby previous experience can be used to develop future products in shorter time scales whilst maintaining the fidelity of a system. The technique should also be able to cope with the inevitable changes to the product over time. This paper describes the use of Object Oriented Technology for the rigorous analysis of a complete system. The resulting model can be used to simulate the behaviour of the system in normal and abnormal conditions, whilst final code may be generated directly from the model and executed on target hardware.