secondhand car vs automobile

secondhand car and automobile both are nouns.

Word	Noun	Adjective	Verb	Adverb
secondhand car	Yes	No	No	No
automobile	Yes	No	Yes	No

As nouns, automobile is a hypernym of secondhand car; that is, automobile is a word with a broader meaning than secondhand car:

secondhand car: a car that has been previously owned; not a new car
automobile: a motor vehicle with four wheels; usually propelled by an internal combustion engine

Other hypernyms of secondhand car include auto, car, machine, motorcar.

secondhand car (noun)	automobile (noun)
a car that has been previously owned; not a new car	a motor vehicle with four wheels; usually propelled by an internal combustion engine

secondhand car (verb)	automobile (verb)
	travel in an automobile