Self-driving cars require an incredible amount of information to operate safely. Tesla and Elon Musk know this well.

Tesla Motors formally launched its long-awaited Autopilot feature on Wednesday, which is not quite a self-driving car, but rather a higher degree of autonomy. One of the new features of Autopilot: Tesla is creating high-precision digital maps of the Earth using GPS.

GPS mapping in cars has existed for years, but that currently only scratches the surface of the data needed for an autonomous self-driving car.

On the left, what currently exists: just the roads themselves. On the right, what Tesla is aiming to do: mapping out every lane. Image: Tesla Motors

Musk isn't alone on this. It's why Apple and Google have been deploying their mapping vehicles around the world, and why Uber tried to buy Nokia's Here maps, before being outbid by a consortium of Audi, BMW and Mercedes-Benz.

Tesla stands apart from the others is the way it's acquiring this data: through drivers. Every Tesla Model S, with Autopilot or not, is connected from the cloud; the company is constantly connecting data from each of its cars. Tesla is using the data it has, and will continue to collect, to develop its maps.

Elon Musk called this a "fleet learning network" where all its cars contribute to a shared database. "When one car learns something, all learn," said Musk.

Musk highlighted a section of I-405 in California, a highway where lanes are terribly marked. Using the information from Model S drivers traversing this specific section of road, Tesla's Autopilot can still function well, even in the absence of lane markings.

He thinks this is the biggest difference between Tesla and its rivals in the self-driving car sphere.

Musk said he believes Tesla is three years away from having a fully autonomous car — not counting the inevitable regulatory battle to get the tech to the public. However, its maps are already quite developed, as evidenced by the map of the San Fransisco Bay Area below.

Image: Tesla Motors

Autopilot comes as part of Tesla's 7.0 software update, which begins rolling out to Model S cars on Wednesday. Autopilot is in something of a public beta, offering automatic steering, lane changes and parking, though Tesla advises drivers keep their hands on the wheel.