stock car vs automobile

stock car and automobile both are nouns.

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

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

stock car: a car kept in dealers' stock for regular sales
automobile: a motor vehicle with four wheels; usually propelled by an internal combustion engine

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

stock car (noun)	automobile (noun)
a racing car with the basic chassis of a commercially available car	a motor vehicle with four wheels; usually propelled by an internal combustion engine
a car kept in dealers' stock for regular sales

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