(Reuters) - General Motors Co’s self-driving unit, Cruise, said on Wednesday it was delaying the commercial deployment of cars past its target of 2019 as more testing of the vehicles was required.

FILE PHOTO: A Cruise self-driving car, which is owned by General Motors Corp, is seen outside the company’s headquarters in San Francisco where it does most of its testing, in California, U.S., September 26, 2018. Picture taken on September 26, 2018. REUTERS/Heather Somerville

Cruise Chief Executive Officer Dan Ammann said the company would expand testing in San Francisco here, and added in a blog post that Cruise was working with Honda Motor Co and General Motors Co to develop purpose-built autonomous vehicles.

Ammann did not say when the company now expects to deploy a ride-hailing service using self-driving vehicles. It had earlier hoped to deploy such a service here by the end of 2019, but in April, GM Chief Executive Mary Barra declined to repeat that goal.

Cruise has raised $7.25 billion during the past year from investors including SoftBank, Honda Motor Co and investment firm T. Rowe Price. As GM and Cruise executives have done in the past, Ammann said Cruise would launch its commercial service when it was sure the vehicles would be safe.

“When you’re working on the large scale deployment of mission critical safety systems, the mindset of ‘move fast and break things’ certainly doesn’t cut it,” Ammann wrote in a post on Medium on Wednesday.

Ammann alluded in his post to broader concerns about the trustworthiness of “Big Tech” and said Cruise was in talks with regulators about how to measure when its technology “will have a net positive impact on safety on our roads.”

Cruise’s decision to formally postpone deployment of self-driving cars this year comes as rival autonomous vehicle companies and automakers acknowledge it will take more time and money than they had expected to make autonomous vehicles safe for unrestricted use on public roads.

The capital and technology challenges of self-driving cars are pushing automakers to forge alliances to share the cost burdens. Volkswagen AG and Ford Motor Co earlier this month said they would partner to develop autonomous vehicles, and invest in self-driving technology company Argo AI. German automakers BMW AG and Daimler AG also have struck self-driving car partnerships.

Alphabet Inc’s Waymo robo-taxi unit has begun offering rides for hire in Arizona, but continues to operate its vehicles with human attendants ready to take the wheel.

Ammann, who took over as Cruise’s chief executive last November, told Reuters last year that developing self-driving cars capable of safely navigating urban traffic was “the engineering challenge of our generation.”

Against what promises to be a long period of development and technology evolution, initial delays would not be that meaningful, he said.

Cruise is working with GM and Honda engineers to develop a next-generation of electric, autonomous vehicles, Ammann said.

“This is not a concept car — hundreds of the best Honda, GM and Cruise engineers are working together on-site in Warren, Michigan, where they are deep into the vehicle development process. This new vehicle completely reimagines from the ground up what a car can be and we can’t wait to share more in the near future,” Ammann wrote.

GM has sought clearance from federal safety regulators for self-driving cars that do not have conventional controls such as a steering wheel. The U.S. Department of Transportation has delayed action on GM’s petition to test such vehicles for more than a year, and earlier this year said it would seek public comments on the proposal.