Cruise control systems are getting more popular in today’s automotive culture but as it is not part of the base packages offered by manufacturers today, it was not available for any model in the past 20 years. The aim of the project is to explore the possibilities of designing a cruise control system that can be retrofitted to vehicles where the throttle is controlled mechanically. I will first analyze a few from the existing systems on the market, then create the system in an adequate simulation environment, where the necessary tunings will be made and the system will be analyzed. The chosen simulation software is AMESim. The model was created using an internal combustion engine, a vehicle body, a transmission and a PID controller. The model was analyzed in different situations. the obtains graphs are included in the final project. The second step in the design is creating the required program for the microcontroller. The final step of the design is creating the circuitry needed for the inputs and outputs. The received circuitry will be fitted on a printed circuit board using a suitable software. Finally I will make suggestions on future use of the microcontroller.