We investigate how the firm's supply chain strategy can enable the firm to achieve responsiveness, i.e., ability to respond to the changes in the customer's requirements rapidly. To answer the research question, we visited the latest assembly plant at BMW and interviewed the managers in charge of plant operations. Applying the grounded theory method, we collected data by interviewing the managers in direct charge of and with thorough knowledge about the assembly operations at the plant. Then, we related empirical observations of the plant's phenomena to each other, to support our propositions. There are several key findings. First, BMW is making a great stride in pursuing mass customisation, i.e., customisation on a large scale. The company exerts enormous flexibility in its assembly operations so as to accommodate fast-changing requirements of the customers. Second, BMW's responsiveness is made possible with coordinated efforts by the company's suppliers, many of whom stay close to the company's assembly plant. Finally, such coordination between BMW and its suppliers will be crucial to enhancing BMW's competitive advantage, not only in terms of market responsiveness, but also in terms of technological innovation in the future.