sport car vs auto

sport car and auto both are nouns.

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

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

sport 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 sport car include automobile, car, machine, motorcar.

sport 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