Final answer:
The metaphorical context in the play develops themes of manipulation, deceit, and cultural exploitation, using Honest Sancho as a representation of the stereotypical used car salesman and a Mexican who has sold out his race.
Step-by-step explanation:
The metaphorical context of Honest Sancho running his "used Mexican lot" like a used car lot develops the play by exploring themes of manipulation, deceit, and cultural exploitation. In the play, Honest Sancho represents the stereotypical used car salesman who uses dishonest tactics to sell his cars. This satire is directed at both the used car salesman profession and the character of Sancho, who is depicted as selling out his own race for personal gain.