How does Fitzgerald use language to create an impression of Gatsby in chapter 4?

Fitzgerald uses various language techniques to create a portrait of Gatsby in this chapter. At the beginning of the chapter, Nick overhears some young ladies on Gatsby's lawn exchanging stories about him: their phrasing—"one time he killed a man"—is typical of urban legends and fairy stories and begins to create a picture of Gatsby as a near-legendary figure, the sort of person others tell tales about.
When Gatsby himself actually makes an appearance in this chapter, it is in his "gorgeous car," lush language which suggests a certain decadence. Gatsby announces himself with a "burst of melody," signifying that his arrival changes the entire tone of any scene he enters. In his movements, he is "peculiarly American," a phrase which creates an image of the archetypal all-American young man, alluding to the American Dream which is so central to this novel. Yet we also see Gatsby's impatient, restless quality in that he "was never quite still," his "tapping foot" or "opening and closing of a hand" betraying the idea that there may be some hidden tension in Gatsby.
The way Gatsby speaks to Nick in the car sustains this impression: his movements make Nick understand "why Jordan Baker had believed he was lying." The way he speaks is "hurried," and potentially "sinister." His "threadbare" phrases obviously do not convince Nick, and the reader feels Nick's "fascination" at the incredible tales Gatsby tells. It is evident that he is lying, but not why: his affected language—"old sport"—is clearly part of the larger fiction. Although Nick is "annoyed" by his behavior, rather than interested, the reader is left with the understanding that Gatsby's life is not at all what it seems.