hot-rod vs automobile

hot-rod and automobile both are nouns.

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

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

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

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

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

hot-rod (verb)	automobile (verb)
	travel in an automobile