Elon Musk has been working up to 120 hours a week recently as he aims to ramp up production of Tesla's mass-market, more affordable car option, the Model 3. What's it like inside the Tesla factory in Fremont, California? YouTube star Marques Brownlee toured the factory and interviewed Musk on August 15th. Here's what he found out:

How Elon Musk spends his time at Tesla

"I think probably a lot of people don't realize I am in the factory in design or engineering meetings or production. So that's like 80, 90 percent of the time," he tells Brownlee in one of two videos of the interview published on Youtube. "I think sometimes people think I spend a lot of time on Twitter. ... I don't know why they would think that … that's crazy. But actually that's almost nothing. "Most of my time is spent, or at least the last several months especially, going around the factory and then working on, say, the paint shop, the body shop where we weld up the body, the final assembly where we put all the parts together ... and then, if I am not here, I am at the Gigafactory in Nevada."

What Musk paid for his Tesla

"No discounts. I actually even pay full retail price for my own cars."

How much of a Tesla is built by robots

"It varies massively depending on what part of the production process — so some parts of it are like 80 to 90 percent automated and then some parts of it are like only 10 to 20 percent automated. "Humans are really good at adaptation and rapid evolution and doing finicky things ... a pretty big mistake was trying to automate general assembly — which is where you put the parts together. ... The robot has got to find the hose, grab it, then connect it to another hose… It's like really hard. A person can just go, doop, done…. When you see it, it is like, wow, it is super obvious."

How many people work in the factory

"This place used to employ like about 5,000 people and now we got like 10,000 people just in this location. ...[W]e have tons of shuttles and we encourage ride sharing. We have the Bay Area Rapid Transit station [that] finally went up. So just like trying to get people here is not easy."

What causes Elon Musk's cell phone to ring at 2 a.m.?

With 24-7 operation happening for the Model 3, "if the robot accidentally crashes and breaks a fixture, then it's like, man, okay, now we have the line down, that's like red alert. And I get called on my cell phone at 2 in the morning … and we are trying to fly a part in from Germany, and we literally had that two days ago."

Accuracy of the robots

"For a big robot, there's a little less precision than a smaller robot ... but say a medium-sized robot will be accurate to 0.2, 0.3 millimeters."

Tesla production robots names

"By the way, these are all named after X-men. … It's Marvel and X-men."

Most popular paint color for Teslas