Japanese automotive giant Toyota is deepening its ties with Guangzhou-based autonomous driving startup Pony.ai. The Japanese company announced plans to invest an additional $400 million in the Chinese firm, an investment that will send Pony.ai's valuation to more than $3 billion.

As part of the transaction, both companies announced that they will be launching a pilot program involving the use of its jointly developed self-driving cars in China. The pilot program will be taking place in the public roads of major cities around the country, including roads in Shanghai and Beijing.

The two companies have been working together to develop autonomous vehicles for public testing since 2019. The latest investment is aimed at accelerating efforts to bring the two companies closer to their intended goals. Toyota announced that they plan to immediately start co-developing new mobility products for future products.

Pony.ai, which also has active operations in Silicon Valley, has been testing its autonomous driving "taxis" in both China and the United States since 2018. The company previously stated that it aims to become the first company to launch a fully autonomous fleet for ride-hailing purposes to the public in China.

For Toyota, the partnership with Pony.ai will allow it to tap into the company's advanced technologies to bolster its own self-driving vehicle program. The Japanese firm has been relatively privy about its autonomous driving plans, but it has released some information to the public regarding some of its progress.

For one, the company previously announced that it should be ready to offer a limited autonomous driving ride-hailing service in downtown Tokyo in time for the 2020 Summer Olympics. Toyota revealed that the vehicles will be equipped with its proprietary "Chauffeur" software, which it described will essentially remove the human from the driving equation depending on the environment.

The Japanese firm also briefly talked about its still-in-development "Guardian" system, which is a driver-assist system similar to the ones found in Tesla's Autopilot software. Neither of the two systems is available in any of its currently released products. The company has also not yet revealed any possible dates for when the new systems will be integrated into its products.

Apart from its investment in Pony.ai, Toyota has also been busy partnerships with other startups to help it develop its future products. In 2018, the company announced a $500 million investment with Uber. The investment was part of its partnership with the ride-hailing giant to also, develop self-driving vehicles.