I can't imagine this is the case, but what if they're building an OS/UI/experience that car manufacturers would build into their vehicles? That would go against everything they've ever done but would be easier and would remove them from direct liability (depending on what features it offered). 30% on a car might be difficult for even Apple to pull off but 30% on a $2-5K option would probably be something most people would spring for. I imagine it would put Google in a tough position, even if they had superior features (like better self-driving).