hot-rod vs motorcar

hot-rod and motorcar both are nouns.

Word	Noun	Adjective	Verb	Adverb
hot-rod	Yes	No	No	No
motorcar	Yes	No	No	No

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

hot-rod: a car modified to increase its speed and acceleration
motorcar: a motor vehicle with four wheels; usually propelled by an internal combustion engine

Other hypernyms of hot-rod include auto, automobile, car, machine.

hot-rod (noun)	motorcar (noun)
a car modified to increase its speed and acceleration	a motor vehicle with four wheels; usually propelled by an internal combustion engine