In June, 20 Geely electric cars with Jing Jin motors were added to cars as part of the State's guest convoy by the Ministry of Foreign Affairs.
While Lyu Huizhao, an official from the ministry, says they're applying for more EVs to promote a low-emission environment, Cai believes developing energy-efficient cars is a way for the Chinese auto industry to become stronger.
Cai also points to a trend of more EVs being used on such occasions.
"I have benefited a lot from policies and the government's resolve to develop the industry," he says.
Cai was born in 1959 in a teachers' family in East China's Shandong province.
He was admitted to Harbin University of Science and Technology in 1978.
After a master's degree in engineering, he began to teach there in 1985.
For a year from 1994, he was a visiting professor in the US and Switzerland.
Cai got a doctorate in electrical and computer engineering from Clarkson University in the US in 1999.
"It was both familiar and challenging for me to go back to being a professor, so I decided to join the industry," he says.
But he was sad to not see too many Chinese faces at international seminars. Finally he met Yu, his future partner, at a seminar.
In 2008, the duo started Jing Jin with 12 people.
"Nothing was easy," says Cai, adding that at the beginning the company could not afford renting a car. He and Yu had to ride on a motorcycle to visit customers.
In 2009, Cai initiated the country's first international seminar on electric motor systems in Beijing.
The next year, the first production line for high-performance electric motors was built in Shanghai - it was also the country's first.
"We encountered a huge crisis in 2013 but stayed alive when we added lines for motors for commercial vehicles," he says.
Now the company has 800 people working in it.
Cai says some of his young engineers can make more than 1 million yuan ($150,000) a year.
Cai has been selected as a scholar for the 1,000 Talents program initiated by the Chinese government to recruit global experts.
With his expertise, he is involved in State plans in terms of technology and energy, and he is devoted to a policy balance among different ministries and local administrations that can make the business environment better.
"One company can't make a business chain and is not strong in global competitions," he says, adding that his spare time is dedicated to training and sharing knowledge.
Cai always carries a small suitcase containing clothes and office equipment.
"I'm always ready to go on a business trip," he says.
Cai says he may be a late entrant in startups, but "young people should get yourselves fully prepared, chances can arrive any time".