The open source software has been proving the viability of the open source business model. The open source hardware represents a straight continuation of open source software and a variation of the wider open source innovation paradigm. Some successes can be highlighted in the field of electronics (e.g., prototyping boards, professional cameras,...). However, the open source hardware has been extending its action towards other horizons. Our paper explores the recent concept of open source car. It is organized in four sections. At the beginning we describe the context of open source hardware and position the concept of open source car. After explaining our methodology and identifying five famous cases of so-called open source cars, we analyze them using an analysis grid. Finally we discuss our findings. We show that the “open source” expression is often unduly used but often covers interesting collaborative practices allowing to foster user-driven innovation and spreading innovations in the automotive sector.