Tesla's CEO Elon Musk believes his cars will soon be able to drive without a driver across the United States.

Tesla cars can already be "summoned" as long as the owners are within three miles of the car. Now, Musk says he thinks that by 2018 his cars will be able to be summoned by their drive from across the country, The Guardian reports.

Tesla's Model S and Model X electric cars just received an update that allows them to be parked automatically in a space perpendicular to the road. The cars are already able to perform parallel parking and park themselves in garages.

"I actually think, and I might be slightly optimistic on this, within two years you'll be able to summon your car from across the country," Musk said at a press conference on Sunday night.

Musk says right now the cars are able to park themselves at their owners' request, but Musk thinks that the task is a step towards self-driving vehicles capable of going long distances.

Tesla warns that the software update does not allow the car to spot every object that could be in its way, like a bicycle hanging from the ceiling of a garage. However, Tesla says that the self-parking feature could help drivers squeeze into tiny spots that they normally would not be able to get out of the car if they parked there.

Tesla cars already have a self-driving Autopilot feature. This feature has been updated to only allow the cars to go near the speed limit, or slightly above it.

Musk says the Model S is "probably better than humans at this point in highway driving."

Musk said the he is not aware of any accidents that have occurred when owners used the Autopilot feature.