How automotive engineering is taking product line engineering to the extreme

Automotive manufacturing ranks among the most extreme instances of systems and software product line engineering (PLE). The product family numbers in the millions, each product is highly complex in its own right, and the variation across products is literally astronomical in scale. This paper explores the aspects that make the domain extreme and the very specific implications they have for PLE. These implications include the need for efficient manufacturing, complexity management, concurrent development streams, globally distributed engineering and production, a hierarchical product family tree, multi-level variation binding, constraint management, and a highly robust and integrated PLE tooling environment. Happily, the PLE paradigm supporting these implications brings about a number of opportunities for analysis and automation that provide efficiencies of production previously unattainable. We focus on one example in depth: The management and automated generation of the many thousands of calibration parameters that determine vehicle-specific software behavior. Throughout, we use the vehicle product line at General Motors, which we believe to be the world's largest, to illustrate and ground our journey through automotive PLE.