Yeah. We're probably just too conservative on our capital projections, but it's turned out to be that we can do this with less capital than anticipated."
Right or wrong, it's pretty clear to me that they are pretty much making educated guesses on capex as they go, as they've adjusted the guidance like 3 times in 2016. From Elon's words, they are clearly guessing on the conservative side. If they end up telling us that they only needed $600 million in Q4 because things are cheaper than they anticipated, I won't be mad.
If you reread the transcript you will see it's full of talk about capital efficientcy, changing the way things are done traditionally, benefits of scaling, etc. They tend to run with themes. I expect this to get used again. If bears (not you, to be clear) want to tell me it's a bad thing when Tesla can arrive at the same result with less money I'm happy to take their money when they get proven wrong in Q3 2017.