Google is fighting Samsung and Amazon for control of the Android ecosystem. As a result, they have to lock down more and more of their apps (leaving the AOSP version to languish) [1]. So while I agree with you that it "worked out pretty well for them" -- namely that Google is still relevant in the Android ecosystem -- I think we can all agree that the Open Handset Alliance is not the real reason for Google's Android success.
That's my premise for saying the Open Automotive Alliance is just Google's attempt to dominate in-vehicle interfaces. I don't think Google's going for a proprietary connector like Apple -- I am glad this is Google we're talking about, so the result is likely just some Android APIs that use bluetooth on a select few car models.
This is definitely not a new era of open hardware in your car or something like that (which would actually be interesting).
Having had the experience of working for one of the OHA companies during the development/launch of Android, the whole thing was less of an alliance/partnership and more of a "here's all the companies contracting or giving their stuff to Android to get the system in launch condition". We were subcontractors.
