For those of you who have not read the Ashlee Vance biography of Elon, it is definitely worth it. They spend a lot of time covering the companies he has run and Elon himself. Very worthwhile. (I cheated and did the audiobook).
In that book, however, it is clear that Elon always over promises on dates.
When he estimates something will take a day, they know it will take a week or more. When he says its a week, well, then that means 6 months.
Elon himself acknowledges this in the book and makes the quote in the subject line, though admittedly I may have paraphrased.
The bottom line is that Elon's time frame for things is never accurate, sometimes off by years! But, at the end of the day, its him trying to drive the business and the world forward. Its his way of managing (some of his management style is absolutely horrible IMHO, but it works for him).
But, the one thing he has proven (besides his poor judge of how long it takes to do anything) is that he always delivers. Will autopilot be out this year? Probably not. Its a very very difficult thing to do and lives re on the line. But, I am willing to bet he does deliver it.
How about the Model 3? Well, i bet we won't see that until late 2018. But, he will deliver it and it will change the game (if the company survives that long). ;-)
So, as I read all these posts about missed deadlines, I just smile to myself. Tesla will get there. I have just learned to add lots of time to whatever he says.