Why does tom make the point that he just drove the coupe from New York and the yellow car not his?

Tom makes the point about driving the coupe from New York to assert his status and to draw a clear distinction between himself and Gatsby. By emphasizing that the yellow car belongs to Gatsby, he seeks to undermine Gatsby's social standing and reinforce his own superiority. This moment highlights Tom's need to control the narrative and assert dominance, especially in the context of his rivalry with Gatsby over Daisy.