You make a great point which is spot-on overall. I wouldn't go as far as saying "the car part doesn't really matter", though. Having a viable primary vehicle

You make a great point which is spot-on overall. I wouldn't go as far as saying "the car part doesn't really matter", though. Having a viable primary vehicle (pun intended) to drive (heh) your technology forward is important. SolarCity + Tesla Battery tech would be much harder to pull off if they didn't have a large in-house initial "customer" in Tesla cars. This will help them identify and solve technology problems, achieve economies of scale to drive down cost, and prove out the viability of these technologies in-market. And the requirement to sign up other customers on the battery side is alleviated early on. Tesla's showrooms are also a great asset in promoting both solar and battery tech for the home, and the car is important in rationalizing the expense of these showrooms (at least for now) as well. Moreover, a very consumer facing brand and product in the car helps tremendously. Anyhow, not to nitpick. You're right on about the overall strategic rationale and why this makes so much sense as a combination. But it's too far to say the car doesn't really matter. In fact, the car is a very important part of the strategy and especially of the nearer-term tactics.