Roadworthiness is the state of a vehicle being in good enough condition to drive safely on public roads — brakes, lights, tyres, steering all doing their job. Testers, police, and insurance people use it. A car can lose its roadworthiness without looking ugly; hidden damage is enough. Though actually, it is a safety-and-law word, not a compliment: a cheap old van can have roadworthiness if the important parts work, and a shiny new car can lack it if the brakes fail. You mostly hear it about cars, trucks, and buses, around tests like Britain's MOT. The adjective is roadworthy.

適路性（夠不夠安全、能不能合法上路；日常多說適不適合上路）