A car owner (right) and a passenger have become good friends. Photos By Zou Hong / China Daily

Zhu Xiaojia, 37, says she now rarely drives her car on workdays since she started to use such apps to commute to and from work more than three months ago. Parking in Beijing's CBD can be hard to find and is expensive, she says, but there is much more to her decision to use the apps than economics.

"It really is tiring driving during rush hours," says Zhu, a course consultant at EF Education First International Language Centers in Beijing, who spends two hours on the road each day getting to and from work.

"Carpooling allows me to talk with a lot of different people. If I drive at the weekends I will also carpool to do my bit for the environment."

Another benefit in carpooling is that it takes cars off the road and can help ease traffic congestion, she says.

Zhu says she usually sits next to the driver, and they chat like friends. She enjoys talking with people from different industries and gets to know about the fields they work in, she says.

Once when she was chatting with a car owner she discovered they had a mutual acquaintance each of them had got to know through car pooling.

Such coincidences are not that uncommon among carpooling app users, even if some put them down to yuan, a Chinese word that refers to people being drawn together by destiny.

"It's like the six degrees of separation theory, which says a friend of a friend can connect any two people in a maximum of six steps," Zhu says.

A decade ago, Shao Fang, 30, worked in Xi'an, Shaanxi province, and came to Beijing on a business trip with her boss and met a friend. Last month she discovered that the owner of the carpool vehicle in which she was a passenger was a workmate of the friend.

"It was amazing to meet a complete stranger who happened to know my friend," says Shao, who works in marketing in Beijing. "Along the way we talked about the various ways my friend had changed over the years."

It is often said that as modernization has swept over China, its citizens are not as close to their neighbors as they once were, but these apps seem to be reversing that trend.

Zhu says her circle of friends has become bigger, including more than a dozen neighbors who work in office buildings close by, and they often get together at weekends, setting up the meetings through the social networking app WeChat.

Ma says he knocked into a young man who lives in the same community as him twice - once when he was the driver, and the other time when he was the passenger. They have a lot in common, and have become friends, playing badminton together at weekends, he says.