I agree with others who are pretty certain that the part 2 is going to be filling in the blanks with the model 3, particularly regarding the control system and dashboard, which Musk has even tweeted about saying that what we've seen is not the real thing, and the real thing being "like sitting in a spaceship".
I expect Part 2 of the Model 3 unveil to fully reveal the control system and display, which has been held back specifically because it is going to be a big deal.
With Musk being such a proponent of autonomous driving, as well as state of the art functionality, with OTA updates and futureproof hardware configurations, I fully expect we'll be told that the base model, initial production model of the model 3 will be fully capable of full autonomous driving, level 5. With a stowable steering 'wheel'.
If he is confident that autonomous driving is only a few years away, there's no way he won't future proof the model 3. He will make sure the design and the hardware will be designed for autonomous driving, so that once it is ready to be rolled out over the air, the model 3 will have everything it needs, and will in fact feel that it was designed for it.
So, I envision a stowable steering system, with some form of flat space in front of the driver to act as a desk or worktop. HUD display information might well be included, but as others have said, the centre screen is sufficient.
The other big part of unveil part 2 will be the details of the AWD performance versions' specs and capabilities.
Showing how advanced, and how future-proofed the model 3 is, as well as how fast and awesome you can make it if you're willing to spend a bit more, will be the kind of reveal that Elon could expect to double or quadruple reservation numbers!
Level 5 would be great, but we're years away from that, more years than the wait will be for the Model 3 to hit production. Level 4 is as high as it will go.
Remember, level 5 means there are no human-operated controls in the vehicle, nor the expectation of them.
Level 0: This one is pretty basic. The driver (human) controls it all: steering, brakes, throttle, power. It's what you've been doing all along.
Level 1: This semi-autonomous level means that most functions are still controlled by a driver, but some (like braking) can be done automatically by the car.
Level 2: In level 2, at least 2 functions are automated, like cruise control and lane-centering. It means that the "driver is disengaged from physically operating the vehicle by having his or her hands off the steering wheel AND foot off pedal at the same time." The driver must be still always be ready to take control of the vehicle, however. So, level 2 means two functions automated. Easy to remember, right?
Level 3: Drivers are still necessary in level 3 cars, but are able to completely shift "safety-critical functions" to the vehicle, under certain traffic or environmental conditions. It means that the driver is still present, but is not required to monitor the situation in the same way it does for previous levels. Jim McBride, autonomous vehicles expert at Ford, said, "the biggest demarcation is between Levels 3 and 4." He's focused on getting Ford straight to Level 4, since Level 3, which involves transferring control from car to human, can often pose difficulties. "We're not going to ask the driver to instantaneously intervene—that's not a fair proposition."
Level 4: This is what is meant by "fully autonomous." According to the DOT, level 4 vehicles are "designed to perform all safety-critical driving functions and monitor roadway conditions for an entire trip." It's what Tesla says will be
available by 2018.
*Level 5: It should be noted that some organizations, like the Society of Automotive Engineers (SAE), have their own
charts that refer to "Level 5" vehicles. This refers to a fully-autonomous vehicle that does not have any option for human driving—no steering wheel or controls.