race car vs automobile

race car and automobile both are nouns.

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

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

race car: a fast car that competes in races
automobile: a motor vehicle with four wheels; usually propelled by an internal combustion engine

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

race car (noun)	automobile (noun)
a fast car that competes in races	a motor vehicle with four wheels; usually propelled by an internal combustion engine

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