Ride-hailing service Uberhas reportedly approached car companies about placing a large order for self-driving cars, according to a report. "They wanted autonomous cars," an auto industry source told Reuters on Friday. "It seemed like they were shopping around."

Audi, Mercedes-Benz, BMW and car industry suppliers Bosch and Continental are all working on technologies for autonomous or semi-autonomous cars.

Germany's Manager Magazin on Friday reported that Uber had placed an order for at least 100,000 Mercedes S-Class cars, citing sources at both companies.

Daimler and Uber declined to comment.

Earlier this week BMW said it was considering launching its own ride hailing service in what would amount to a rival business to Uber.

A key hurdle to driverless cars has been the question of liability in the event of an accident. Some countries along with some U.S. states have granted permission to test self-driving cars.