Why did Mahayana Buddhists call their tradition the Great Vehicle?

The term Mahayana, which translates literally to "Great Vehicle," was adopted by adherents of the tradition to establish the superiority of their teachings over other Buddhist schools. By designating their movement as the "Great Vehicle," Mahayana followers sought to distinguish their path as a more expansive or inclusive approach to enlightenment compared to earlier schools, which they sometimes characterized—often critically—as the "Lesser Vehicle" or Hinayana.123

Historically, this classification was a rhetorical device intended to assert the authority of the new Mahayana sutras, which were compiled centuries after the Buddha’s death. These texts presented innovative ideas, such as the universal accessibility of awakening and the ideal of the bodhisattva—one who seeks to become a Buddha to liberate all beings. Because these schools accepted these new scriptures as the authoritative word of the Buddha, they viewed their "Great Vehicle" as a more comprehensive means of achieving ultimate liberation for all sentient beings.1345