Why did Steinback include the "car talk" segment in chapter seven of "The Grapes of Wrath"?
Very astute question! You have to notice that the longer Chapter 8 has been framed by two smaller chapters in Chapter 7 and Chapter 9, both of which shift the narrative from the Joad family to other topics, firstly in Chapter 7 to the used-car salesman who is delighted in the way he is able to sell terrible cars for high prices to the farmers, and then Chapter 9 where the tenant farmers are looked at more widely, and what it costs them to move and how their position is exploited by pawnbrokers.
Both of these Chapters that surround our introduction to the Joad family present one of the book's major themes - the ability of man to commit inhuman acts against their fellow man for personal profit. It is clear that the narrative is strongly critical of the used-car salesman who willingly deceive the tenant farmers and play on their ignorance with cars to sell them terrible vehicles for what little money they have left. It is this theme of inhuman acts that the Joad family tries to stand against throughout the novel. However, throughout the novel, the privileged few refuse to give any of their wealth away to help others. This belief is in sharp contrast to Jim Casy's belief that men must act for the good of all men, and the attitude of the Joad family, who willingly share what food they have with others. Steinbeck suggests in the novel that moral order is dependent upon charity and this kind of selflessness.