Pony.ai, an autonomous driving technology startup, said on Monday that it has completed the first close of its Series D financing.

The company did not offer the sum it has raised in this round, saying that details will be announced when the full financing round is closed.

It said its valuation has surged to $8.5 billion, up 65 percent from its Series C financing round, and its current cash flow reaches nearly $1 billion.

Pony.ai said the proceeds from the funding will be used to further augment Pony.ai's hiring, investment in research and development, global testing, enter into strategic partnerships, and accelerate its efforts towards mass production and mass commercial deployment.

"Our technical development and balance sheet strength go hand-in-hand in allowing us to significantly expand our hiring in 2022, open up a number of new autonomous vehicle global testing and operation sites, progress our strategic partnerships and rapidly grow our fleet," said James Peng, Pony.ai's co-founder and CEO.

Founded in 2016, Pony.ai now has a fleet of over 200 vehicles in China and the United States.

It was the first autonomous driving company to conduct autonomous trucking tests on an open highway in China, and one of two companies permitted to conduct driverless tests and charge fees for public robotaxi services in Beijing.

Tiancheng Lou, Pony.ai co-founder and CTO, said Pony.ai's virtual driver is "now equal to or superior to a human driver" in most circumstances.

"We're confident in our autonomous vehicle tech readiness as we rapidly scale toward robotaxi and robotruck commercialization and mass production," he said.

Pony.ai has formed partnerships with leading carmakers including Toyota, FAW Group and GAC Group.