Active Safety (AS) and Advanced Driver Assistance Systems (ADAS) can nowadays be considered as distributed embedded software systems where independent microprocessor systems communicate together using different communication protocols. Typical AS or ADAS functionality is then realized by several microprocessors communicating with each other. AS and ADAS systems interact with other Electronic Control Units in a vehicle via communication networks and gather vehicle's surroundings via camera, radar or laser sensors. Quality assurance and safety standards combined with increasing complexity and reliability demands related to vision sensing, radar sensing and data fusion, often together with a short time to market, make the development of such systems challenging. As the number of important road scenarios for the system grows, mathematical modelling and computer simulation become important engineering tasks that aim to assure the required quality and compliance with safety standards. This paper presents a simulation approach and its practical realization on a large scale in production stream projects. It is shown that the simulation can be performed on Model-in-the-Loop, Software-in-the-Loop and Hardware-in-the-Loop levels with different configurations in which some of the system components are real and some are simulated. The possible test scenarios arising from the interactions of the driver, vehicle, traffic situation and environment can be recorded during test drives and then reproduced in the simulation environment, and they can also be generated virtually. The paper illustrates both how to perform the simulation in real-time and non-real-time on a multicore processor machine in order to speed up the simulation time.