designed to be transported on top of an automobile
cartop in American English
(ˈkɑːrˌtɑp)
adjective
of a size and shape suitable for carrying on the top of an automobile
Also: cartoppable
Word origin
[1945–50; car1 + top1]This word is first recorded in the period 1945–50. Other words that entered Englishat around the same time include: RNA, individual medley, poison pill, spin-off, synchronized swimming