Nissan is using self-driving cars to tow new vehicles from the factory floor onto transport ships in Japan.

According to the AP, some new vehicles at the Nissan plant in Oppama are towed onto transport ships for delivery using self-driving electric Leafs. The autonomous cars have the ability to stop for other vehicles, navigate parking lots, and place new cars near the transport ships. They aren’t quite ready for end-to-end transportation, however; human drivers are still required to take the Leafs to the particular wharf where they need to be.

Sometimes, the autonomous vehicles run into trouble. AP writer Yuri Kageyama reported that one of the two Leafs used during a demonstration on Dec. 5 refused to move.

However, using self-driving technology at the factory is also teaching Nissan what it needs to do to get self-driving cars on public roads. Although self-driving vehicles are currently illegal on public roads throughout Japan, Nissan can legally use them on their private property. The company hopes to have more autonomous tow cars in the plant in Oppama by 2019, as well as in overseas plants, and to continue to test them for driving on public roads. Future versions of the Leafs used in the factory may also be able to tow new cars all the way onto the transport ships.

As is the case with many vehicles from major automakers around the world, autonomy is beginning to seep into cars produced in Japan. Assistive driving, such as cars which can put on the brakes before a collision or stay inside a lane on a highway, are available commercially in the country.