Vehicle electronics systems will continue to become more complex and larger in scale. This causes their development to be conducted without control. As a result, system development involves things becoming intertwined with each other, like spaghetti. This has made it extremely difficult to develop an entire electronics system coherently and efficiently, from functional architecture down to physical architecture. There is thus a need to reform the development style of the electronics field to a style which will continuously and efficiently generate high-quality products.This will be achieved by dividing development into functions and components.Function development refer to developing functions that OEMs want to equip in the vehicles, that is, “what to make. Components development refers to “how to realize these components. For this activity, it is necessary to promote and accelerate platform-based development looking down at entire electronics systems. The author would like to explain component development for Tier 1 in the platform-based development for the main body.The development methodology focusing on single component used today has been facing an additional challenge because of increasingly strict requirements for optimum multi-components. To address these challenges, we have been working on developing virtual development of components by modeling technology.In order to achieve optimum electronics systems, it is necessary to build many real devices and evaluate the performance of systems. However, it is also becoming necessary to build virtual devices because of the increasingly complicated and large-scale systems. Therefore, the physical architecture connecting functional architecture and microcontroller or peripheral LSI should also be applied to virtual development. On the other hand, virtual technology is needed to apply fault injection for the design of functions as well as safety. Therefore, we have been using system level modeling and simulation technology with System C language which provides the concept of time.In the phase of physical architecture design, how to decide the architecture of components, i.e. what microcontroller, software, peripheral LSI, etc. to use is very important, as is how to design a safety monitoring system to meet safety requirements.The important requirements of a virtual development environment are hardware and software optimized partitioning determination, microcontroller processing load estimation, and failure simulation. These requirements can be met by designing each functional model of systems such as AD converter and drive circuit, connecting these models as a system and simulating the behavior of the whole system. Virtual development is also efficient for safety design. Because the data transferred in the system can be changed to failure data forcibly by covering functional models with failure models, this makes it easy to achieve fault injection.