One of the most important decisions that Elon Musk made about Tesla—the defining imprint that led to its success and its impact on the auto industry—was that it should make its own key components, rather than piecing together a car with hundreds of components from independent suppliers. Tesla would control its own destiny—and quality and costs and supply chain—by being vertically integrated. Creating a good car was important. Even more important was creating the manufacturing processes and factories that could mass-produce them, from the battery cells to the body.
