I've noticed several questions on this thread about manufacturing. Since I have worked in auto manufacturing, I will share some thoughts in the following areas: EV Assembly is Simpler; Humans are inefficient; Musks' Desk by the End of the Assembly Line; and Tesla is Smarter than Toyota.
This is intended as a VERY high level overview, expect many details to be glossed over.
EV Assembly is Simpler: Electric vehicles are slightly simpler than Internal Combustion engines. This does make EV Assembly slightly simpler... but not much.
Automotive Assembly plants consume parts and make finished vehicles. Assembly plants have three main areas: Body, Paint, and General Assembly. Tesla's Fremont plant has these 3 areas.
What is because Tesla makes EVs? Not the Body Shop, not the Paint shop. Is General Assembly simpler? Not by much. GA is split in two areas - Trim and Chassis. Trim no less complex on an EV than ICE. Part of the Chassis process is simpler.
So, part of 1/2 of 1/3 of the Assembly process is easier in the Assembly plant; call it 10% less complex (1/6 = 17%, but only part of that 17% is simpler).
Humans are Inefficient (also, Four Function Robot):* Efficiency, and engineering is all about trade-offs. In my opinion Musk will not be able to automate his way to 500k vehicles per year.
Humans are often perceived as inefficient because: software engineers (and most of the people reading this) tend to value their time highly and strongly dislike repetitive tasks. The perception is that if the task is automated, it is a better use of a persons' time. This can be true. This is why all auto OEMs have some automation in manufacturing.
Humans, however are better in a number of ways: humans are great at learning new tasks quickly and cheaply, humans require much lower capital expenditure to hire (they may be more expensive in the long run, but 2 years is not the long run)
Automation can also be inefficient depending on the parameter chosen. At one point Tesla had a multi-function robot that changed it's "hand" for each vehicle to perform different task. Changing the hand takes time, which Tesla cannot afford if they want to build 500k vehicles/year. Yes, you can simply add more robots, but that costs money.
As Tesla has been setting up its manufacturing process, it may have in mind future expansion and speed-up; but it has been solving current problems. Automation in particular can be troublesome to speed up (most definitely following the 80/20 rule). Portions of the assembly line may have to be re-structured to allow parallel operations, which can be expensive and time consuming.
Also, the assembly operation(s) in question have to be engineered with automation in mind (else it will be amazingly expensive). This is entirely possible, but I don't see a major breakthrough in 2 years alongside a major vehicle launch.
Musks' Desk by the End of the Assembly Line (and Tesla is Smarter than Toyota): This item in particular makes me shake my head in disbelief. On a recent earnings call, Musk said that his desk is next to the end of the production line [desk]. This suggests that Musk is attempting to inspect his way to quality. Do you know who tried to inspect their way to quality? GM (among many others). Do you know who has a good reputation for quality? Toyota. [quality]
In addition (and more pertinent to the speed-up question), quality has a quantity all its own. If you use high quality parts, you can put them together more quickly and more reliably, and thus in higher numbers. If you produce high quality vehicles, you can ship them more quickly, and again, in higher numbers.
In other words, the defects are not being added to the vehicle at the end of the assembly line, and they cannot easily be removed at the end of the line. Can you test your way to high quality software? Can you inspect your way to high quality vehicles?
[desk]: http://qz.com/676127/no-need-to-worry-elon-musks-desk-is-rig...
[quality]: 1. Musk is certainly doing more than just inspection, but his words send a very naive message. 2. GM and other companies perceived as low quality have actually caught up to, and surpassed Toyota. http://www.jdpower.com/press-releases/2015-us-initial-qualit...