Final answer:
The phrase in question is a fragment as it does not have a subject or main clause, which is necessary to form a complete sentence.
Step-by-step explanation:
The phrase 'Drivers completely ignore my vehicle' is a fragment because it lacks a subject and expresses a complete thought. In English, a sentence should have at least a subject and a verb that conveys a complete thought. Fragments often occur when the main clause or subject is missing in the sentence. In this instance, the sentence likely lacks a main clause to clarify who or what is being ignored by the drivers.