car from the ground up. When you buy a Tesla, you don't just buy the vehicle. Instead, you get a complete system consisting of the car, battery, charging network, and on-board software. This type of systems thinking is not new in engineering; it has been cultivated since the mid-twentieth century under the term systems engineering. Originating in the aerospace industry, it has been adopted by other industries and further developed there for their own purposes. As the story of the Asian OEM shows, however, the application of systems engineering is neither self-evident nor simple. Interdisciplinary approach for complex development tasks Systems engineering is an integrated approach that views products or services as an interconnected system. The system concept applies to several levels. For example, each product consists of differ- ent components, each of which is again understood as a system – in this case as a subsystem. Systems engineering views product components as subsystems that are developed together with the higher- level system. However, even products do not stand alone in almost all cases but are integrat- ed into a higher-level system – such as associated products and services as well as stakeholders. Even legal regulations can be part of the higher-level system. For example, autonomous cars must comply with road traffic regulations. In general, systems engineering ana- lyzes how the components of a system are interrelated and interact in the con- text of larger systems. This is not just about engineering in the narrow sense. As an interdisciplinary approach, it is used today to develop successful prod- ucts or services in many areas. It aims to define customer needs and the necessary functionality early in the development process and to develop the product in collaboration with the customer. Technical, economic, legal, and social requirements of all stakehold- ers are incorporated into the develop- ment process. In addition, systems engineering today takes into account the entire product lifecycle, from the design phase to recy- cling and/or disposal. This applies above all to smart, networked products and services. They are connected to the Internet of Things (IoT) and use artificial intelligence (AI) as a product feature. They are referred to by the technical term System-of-Interest, as they are the actual product that forms the core sys- tem for development. Risks due to excessive product complexity The design of products as a system of systems causes different interactions between the system-of-interest, its sub- systems, higher-level systems, and neighboring systems. As a result, it becomes very complex and comes with three risks: system errors, reductionism, and over-complexity. System errors: Systems-of-interest often possess so-called “emergent“ properties or behaviors. They are not inherent in the individual subsystems but emerge only through their interac- tion with each other and with the envi- ronment. As a result, system errors up to total failure can occur under certain boundary conditions. They are diffi- cult to detect by tests or simulations. Consider this typical example from the 2020 recall list of the German Federal Motor Transport Authority: “In the event of airbag deployment at an interior temperature below -15°C, there is a possibility of damage to the airbag.“ These environmental conditi- ons have obviously not been conside- red or tested, so a malfunction may occur in the event of an accident. Reductionism: The complexity of an overall system can be reduced by developing individual components separately. However, this comes at the price of turning these compo- nents into a black box uncoupled from the overall system. In the auto- motive industry, for example, this is the case with software components, like Android Auto or Apple CarPlay. They are designed by software manu- facturers and controlled via interfaces designed by them. The OEM must be able to rely on there being no internal errors in the black box. It is therefore heavily dependent on the supplier and the functions it provides. The counterexample is well known; Tesla's Experience central on-board software, including navigation and entertainment, is a purely in-house development. Only the map material comes from Google. Over-complexity: A long tradition of existing products often results in over-complexity due to incremental extensions. Manufacturers merely extend the product “on top“ by adding functions. One example is the more than 100 control units in modern cars, depending on the type of vehicle. They each have their own small computers and are networked with each other to coordinate their actions as needed. The complexity of today's vehicles is difficult to master and also difficult to replace because of the heavy dependence on compo- nent developers. It is apparent that systems engineering is of central importance to industrial pro- duction. The increased emphasis on networking and software alone increases the complexity of modern products. It is necessary to employ an integrated approach for analyzing the behaviors and elements of the overall system. Systems engineering is therefore not a process, but rather a way of thinking to understand complex problems. It is applicable to all phases of the design and lifecycle of products. It also provides a higher-level perspective with the goal of completely redesigning products or services. The V model: Development with systems Product development with systems engi- neering is most easily represented by a process model depicted as a “V.“ Here, the left leg of the V model shows the design phases, while the right leg shows the test phases. The V model is recommended in the VDI/VDE guideline VDI/VDE 2206 as part of the “development methodology for mechatronic systems.“ The starting point (top left) is systems requirements in the form of a development order, which are also the evaluation benchmark for the end product. The systems archi- tecture is then designed, in which, among other things, the overall func- tions of the system are broken down into sub-functions. 2022-1 ProductDataJournal 45