sports car vs auto

sports car and auto both are nouns.

Word	Noun	Adjective	Verb	Adverb
sports car	Yes	No	No	No
auto	Yes	No	No	No

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

sports car: a small low car with a high-powered engine; usually seats two persons
auto: a motor vehicle with four wheels; usually propelled by an internal combustion engine

Other hypernyms of sports car include automobile, car, machine, motorcar.

sports car (noun)	auto (noun)
a small low car with a high-powered engine; usually seats two persons	a motor vehicle with four wheels; usually propelled by an internal combustion engine