Adjective clauses are those that modify, describe or give more information about nouns. We can identify them because they are usually placed right next to the noun they describe. Many of these clauses usually begin with a relative pronoun (who, whom, whose, that or which) or a relative adverb (when, where or why), however, these words can be omitted, just like they are omitted in the adjective clause of the sentence.
In the sentence, the adjective clause is “I drive” because it is giving us information about the noun “The car.” This clause is also “defining” because it gives us essential information to identify the noun; without this clause, the noun could not be understood and the idea of the sentence would not be complete.
