On Wednesday night Elon Musk grandly told audiences at the Code 2016 conference that we might be living in a simulated universe. That comment has certainly sparked attention, but he said something else that's still got us scratching our collective head: when asked about self-driving cars, Musk said that he considers it a "solved problem," and that "we are probably less than two years away" from safe autonomous driving.

This timeline is consistent with one that he gave Ars in 2015, but the head-scratchy bit is that every other expert we've spoken to thinks true self-driving cars (Level 4 autonomy according to the National Highway Traffic Safety Administration) are at least a decade out. NHTSA defines a level 4 autonomous car as one that "is designed to perform all safety-critical driving functions and monitor roadway conditions for an entire trip. Such a design anticipates that the driver will provide destination or navigation input, but is not expected to be available for control at any time during the trip. This includes both occupied and unoccupied vehicles." Even Google's experimental self-driving cars are classed as Level 3 by the agency.

Autonomous driving experts we've consulted at Audi, BMW, Ford, Mercedes, and Volvo (all of which have extremely active self-driving research programs) have consistently told us the same thing: it's comparatively easy to make a car drive itself on a highway where every car is going the same direction and there's no pedestrian traffic. But a car that can drive itself through a busy urban interchange—think Manhattan or Mumbai at rush hour—is closer to 2030 than 2020. Even sensor OEM Mobileye, which supplies Tesla with some of its autopilot hardware, won't have its Level 3-ready EyeQ5 system on a chip ready until 2020.

Does Musk know something that no one else in the industry knows, or is he being overoptimistic because good PR is helpful for attracting investment? It is true that Tesla is getting a vast amount of real-world driving data from the tens of thousands of Model S and Model X vehicles on the road, which might give it more data to work with than other OEMs. In May, Tesla head of autonomous driving Sterling Anderson revealed that over the past 18 months the company had collected 780 million miles of driving data from Model S and Model X vehicles, and that it gets another million miles of data every ten hours.

That is a truly vast amount of real-world driving data. Google, which also has an advanced self-driving car program, has only collected 1.5 million miles of data from its fleet of 55 four-wheeled robots. It's tempting to dismiss Musk's claims as marketing, particularly since Tesla certainly isn't immune to missing self-imposed deadlines—but the odds here seem to be in Musk's favor.