GM is partnering with Lyft to test a fleet of self-driving Chevrolet Bolt electric taxis on public roads. In January, GM invested $500 million in Lyft to establish a network of on-demand autonomous vehicles in the U.S. The self-driving Bolts are expected to join Lyft later this year.

Details of the autonomous-taxi testing program are still being worked out, according to a Lyft executive, but it will include customers in a yet-to-be disclosed city. Customers will have the opportunity to opt in or out of the pilot when hailing a Lyft car from the company’s mobile app.

The collaboration, first reported in the Wall Street Journal, comes a few months after GM invested $500 million in San Francisco-based Lyft, and spent $1 billion buying another San Francisco company, Cruise Automation, a developer of autonomous-driving technology.

Google and Fiat Chrysler Automobiles also recently teamed up for self-driving minivans.

Earlier this year, Google, Ford and Uber, Lyft’s larger competitor,formed a coalition to push for federal support for self-driving cars.

The Chevrolet Bolt, which will have a 200-mile range, is expected to go on sale later this year for around $30,000 after federal and state rebates.