The requirements to system and software development tools brought up by the automotive industry differ from the requirements that other customers have. The important catchwords here are heterogeneity of suppliers, tools, technical background of the engineers, and – partially resulting from the just mentioned – the overall complexity of the systems that are built up. There are multiple suppliers delivering multiple programs and units, and all these are to be integrated into a car that has to meet a huge number of constraints regarding safety, reliability and consumer demands. This paper shows what the design of electric and electronic car systems is and has to be like, and what qualifications the methodology and the process therefore has to meet. From these two points a collection of requirements to the tools and the tool chain is derived, with a special focus on simulation tools. 1 Why another Paper about Requirements? In principle all big, complex systems have equal requirements...