What is the simple subject in sentence there are many cars parking lot?

The simple subject in the sentence "There are many cars in the parking lot" is cars.

Here's why:

* Subject: The subject of a sentence is the person, place, or thing that performs the action of the verb.

* Simple Subject: The simple subject is the main noun or pronoun that performs the action.

In this case, the verb is "are" (a form of "to be"), and the cars are the things that exist in the parking lot. "There" is an expletive, a word that fills a grammatical position but doesn't have a real meaning in the sentence.