When you put them together, 搭便车 (dā biàn chē) literally means “to take a convenience-car.” It perfectly captures the informal nature of getting a lift that happens to be on someone's way.
The concept of 搭便车 reveals a lot about Chinese social dynamics. Literally, “hitchhiking” (in the Western sense of standing by a highway with your thumb out to get a ride from a total stranger) is not a common or well-understood practice in China. Safety concerns and a different culture of mobility mean that you rarely see it. Instead, 搭便车 almost always happens between acquaintances, colleagues, or friends. It's an informal act of mutual help. The term's true cultural weight, however, is in its figurative meaning, which aligns perfectly with the Western economic concept of the “free-rider problem.” In a collectivist-leaning culture where group harmony and fair contribution are highly valued, being labeled as someone who “搭便车” is a significant criticism. It implies you are selfishly benefiting from the group's labor (in a company, a family, or society at large) without pulling your own weight. This is a much more common and powerful usage than the literal one.
搭便车 is used constantly in both casual and formal contexts.