CAR 54-Q was a starship that was registered for Federation travel in the late 24th century. In 2370, the captain of this ship was R. Savage. The starship's point of departure was Arlington IV. The starship arrived at Deep Space 9 on stardate 47563.1. The CAR 54-Q was listed on the space station's arrival roster. (DS9: "Whispers", production art)

This starship was only mentioned in writing.
The name of the ship was presumably an in-joke homage to the 1960s comedy show "Car 54, Where Are You?" DS9 guest star Albert Henderson was a regular on that show.