sport car vs sports car

sport car and sports car both are nouns.

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

As nouns, sport car and sports car are synonyms defined as:

sport car and sports car: a small low car with a high-powered engine; usually seats two persons

sport car (noun)	sports car (noun)
a small low car with a high-powered engine; usually seats two persons	a small low car with a high-powered engine; usually seats two persons