General Motors' Cruise Automation announced Tuesday it raised another $1.15 billion in its latest investment round, bringing the firm's valuation to around $19 billion.

Those who contributed to fund GM's self-driving car efforts further include GM itself, the SoftBank Vision Fund, and Honda. The latter two previously committed substantial amounts of money to Cruise. Japan's SoftBank Vision Fund announced a $2.25 billion investment last May; Honda said in October it would partner with GM to build a purpose-built self-driving car and invest $2.75 billion over the next 12 years. Of Honda's initial investment, $750 million represented an equity stake.

GM to acquire San Francisco-based Cruise Automation

GM to acquire San Francisco-based Cruise Automation

"Having deep resources to draw on as we pursue our mission is a critical competitive advantage," Cruise CEO Dan Ammann, who took over the subsidiary from Cruise co-founder Kyle Vogt earlier this year, said in a statement. In other words: self-driving cars are expensive.

The nearly endless number of investments have reaped few rewards from self-driving cars but promise the world when the technology finally arrives. Automakers, technology companies, and businesses all may benefit from self-driving cars as they change the way people move. Unlike some of its rivals, Cruise has not backed down on the idea of overestimating the arrival of self-driving cars. GM previously committed to commercializing self-driving cars this year, though there has been little information on a commercial service thus far.

Chevrolet Bolt EV Cruise Automation test mule in San Francisco

Chevrolet Bolt EV Cruise Automation test mule in San Francisco

With the latest round of investment closed, Cruise added the company has raised $7.25 billion in the past year. Expect that number to grow as more investors seek a piece of the self-driving car pie.

Other leading rivals in the self-driving space include Uber's Advanced Technologies Group (also includes SoftBank as a primary investor), Alphabet Inc.'s Waymo, Aurora Innovation, Argo AI, plus automakers BMW Group, Daimler, Ford, Tesla, Toyota and the Volkswagen Group.