racer vs motorcar

racer and motorcar both are nouns.

Word	Noun	Adjective	Verb	Adverb
racer	Yes	No	No	No
motorcar	Yes	No	No	No

As nouns, motorcar is a hypernym of racer; that is, motorcar is a word with a broader meaning than racer:

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

Other hypernyms of racer include auto, automobile, car, machine.

racer (noun)	motorcar (noun)
an animal that races	a motor vehicle with four wheels; usually propelled by an internal combustion engine
slender fast-moving North American snakes
a fast car that competes in races
someone who drives racing cars at high speeds