BERLIN—German auto supplier Bosch GmbH and the Dutch digital mapping company TomTom have agreed to work together to develop high-definition digital maps needed for self-driving cars, the companies said Tuesday.

“We will only be able to have self-driving vehicles on the highway in 2020 with highly accurate maps,” Dirk Hocheisel, Bosch’s general manager, said in a statement.

Under the partnership Bosch will provide technology to make TomTom’s digital maps more accurate and better able to incorporate data produced by an automobile’s systems.

The arrangement comes as car manufacturers push to perfect autopilot systems and deploy some features already, such as self-parking cars or technology that allows cars to automatically stay in a lane while traveling on the highway at high speed. A major component of self-driving cars is the high-definition digital map, which produces a 3-D real-time digital representation of the environment.

As part of this drive, BMW AG , Audi AG and Daimler AG are in talks with Nokia Oy to acquire the Finnish group’s Nokia Here digital mapping service, the world leader in high-definition maps. People familiar with the takeover talks say negotiations are in the final stages but that it isn’t clear when a decision will be made.