Here is a cool graphic from Financial Times that shows the complex web of alliances between various auto makers (registration required).
The question in my mind is how do you synchronize and manage R&D is this environment? Any learning whether from innovation or from risk/failure in one organization has to filter through to all related – because their products, subsystems and components are tied together at the hip. How does one keep track of all of that? Maintaining that flow Managing IP and all the confidentiality will also be a nightmare.