Much of the auto industry is based on buying components like these from one of small group of suppliers. Many are German or Japanese. It has the advantage of making it easier for new comers like Tesla: They can just buy things like wipers from the same companies as everyone else, and focus their engineering efforts on the unique parts.
Very interesting article about the early years of Tesla, but there's a weird jump at the end from the Roadster just shipping, to announcing the obscure D-version of Model S.
