What is the purpose of the noun phrase in the sentence? The little blue car had a ticket on the windshield
# not sans

The purpose of the noun phrase "the little blue car" is to be the subject of the sentence. The noun head of this NP is premodified by an AdjP (adjective phrase) "little blue". What is more, the predicate is a verb predicate whose head is the verb "had". This verb is a transitive verb which selects two arguments: one which functions as the subject of the sentence, the NP already analized, and another NP which functions as the direct object ("a ticket"). The PP (prepositional phrase) "on the windshield" functions as an IP modifer indicating location.

Explanation:

roses are red,

violets are black,

for what you said,

i hope you sit on a big fat tack.

it probably should so i can spam dank memes