Abstract This paper reports a study into the use of US patents to analyse responses to regulatory change in the automobile industry. Confirming that patents are a rich indicator of technological development, it focuses on the development of the electric vehicle (EV) and, in particular, the identification of networks of firms developing EVs. A key finding of the study is the way that car firms have formed links with competitors and with firms and inventors outside the automobile industry, in order to develop this technology. This contradicts the normal product development methods in the automobile industry, and is attributed to the substantially different technologies required for EVs. In addition, the limitations of defining patent searches in terms of products––rather than technologies––are discussed.