A subcompact is a very small, cheap car — smaller than a compact, which is itself already a small car. It is a size category from the American car market, where cars are sorted roughly as full-size, mid-size, compact, and subcompact. Think of the little city cars Taiwanese drivers know well: a Toyota Yaris or a Honda Fit sits in this class. The word works both as a noun ("she drives a subcompact") and as an adjective before a noun ("a subcompact hatchback", "the subcompact market"). The word is North American. British writers say small car, city car, or supermini instead, and would not naturally reach for subcompact. So it is really a piece of American consumer vocabulary, and it comes with a whole feeling attached: cheap to buy, cheap on fuel, easy to park, but cramped, noisy on the motorway, and what you drive when money is short or you are young. American writing plays on that. One more place you may meet it: guns. American firearm makers use subcompact for the smallest pistol size, below compact, meant to be carried hidden. Same logic of naming, entirely different object — the context will always make it clear.

（美式）小型車、迷你車（比 compact 小型車還小的等級，如 Yaris、Fit 這類）