Here are a few thoughts I have based on things Tesla has said and my understanding of what they are trying to accomplish.
There are two lines production lines at Fremont plant. The original Model S line and the new Model S/X line.
New factory line being used for both Model S/X.
Cautions during earnings call that supplier delays could result in 800 fewer cars built in 2015
Rapid rise in production towards end of 4th quarter
50K-55K production target for 2015
Gigafactory 1 will begin initial production in 2016
Gigafactory 1 is "like a product" that can be replicated
Potential to build Model 3 in multiple locations
According to various factory tour reports, the new Model S/X line is a complete second line, apart from the original Model S line.
I was somewhat surprised that Tesla shifted Model S production onto the new combined Model S/X line. I had expected that they would continue to build Model S on the original line until the Model X ramp had completed. This would have diminished impacts to Model S production and let them focus on Model X production on the new line. However, this strategy would have likely caused some delays when shifting Model S production to the new line during a time when they would be trying to maximize Model X deliveries.
Taking the time now to validate the new line for Model S and ramp both models on the new line makes sense for a smoother delivery flow in 2016. This also makes sense in terms of accelerating Model 3 production. I believe that by shifting all current production to the new line, they can give the Model 3 engineers a production line to begin building Model 3s on. It would seem to me that having access to that facility would enable them to build prototype cars more quickly and iterate on design choices rapidly.
The ramp for the Model S and X to reach 80-90,000 cars (combined) in 2016 will be helped by the initial output of the Gigafactory. Over the next 5 years, the ramp of Gigafactory output will pace the ramp of overall Tesla production. Throughout this five-year ramp, a percentage of the Gigafactory output will also go towards Powerwall and Powerpack production. If I recall correctly, the new line is supposed to be able to get up to 150,000 or so Model S/X per year. Model 3 will ramp to approximately 350,000 over a 2-3 year period--but I don't think that will be on a single line.
The Gigafactory is designed with multiple production lines. It is flexible so that some lines can handle different chemistries. And it is being built as a product so that they can build more Gigafactories as the capacity is needed. Applying that same thinking to the Model 3 production, I think they will build multiple parallel lines to produce the Model 3 in volume. One or more of those will be in the Fremont plant, but once they've proven the build process, they should be able to "productize" the factory line and replicate it in other locations--either domestically or abroad.
I am thinking that production of both Model S and Model X are going through a ramp on the new line. Model S will be a rapid ramp during August and early September bringing it back up to 1000/week. I think the Model X begins production for deliveries (vs. testing and demonstrators) in the last week of August, producing 100/week, possibly ramping to 200/week in the last couple of weeks in the quarter. This puts combined Model S/X production approximately the same as Q2 with total cars per week exceeding 1000 for part of September.
In Q4, Model S production gets cut back to 800/week, with more time being spent on ramping Model X production--hitting 800 Model X per week by December. Total X produced in 2015 around 8000. Total Model S around 43300 for a total combined of 51300, sitting comfortably in the range guided on the earnings call.
Since a one week slip anytime during the ramp due to supply issues will push a week's production off the end--that week delay would cause a loss of approximately 800 cars--as mentioned in the earning call. If the delayed part is one that is shared between S and X, then that could also affect S deliveries by a similar amount and could bring the number down closer to the 50K lower guidance.