The current research aims to design a proposed system for determining and controlling the speed of cars on different roads, based on Arduino and the standard OBD II communication protocol used in most modern cars, which operate with the electronic Throttle air gate. This is due to the large number of car accidents that killed millions of people around the world, and the research showed the possibility of using the proposed system in school and populated areas, as well as using it in school buses, which maintains students` safety, by controlling the speed of cars and buses in these areas so that drivers cannot exceed the prescribed speeds. The proposed system was designed and tested on different types of cars such as Toyota, Volvo, Peugeot and other cars. A test was conducted for the accuracy of the system in determining speeds and locations, and its accuracy reached more than 98%.