pace car vs auto

pace car and auto both are nouns.

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

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

pace car: a high-performance car that leads a parade of competing cars through the pace lap and then pulls off the course
auto: a motor vehicle with four wheels; usually propelled by an internal combustion engine

Other hypernyms of pace car include automobile, car, machine, motorcar.

pace car (noun)	auto (noun)
a high-performance car that leads a parade of competing cars through the pace lap and then pulls off the course	a motor vehicle with four wheels; usually propelled by an internal combustion engine