While Starr and Khalil's friendship is the foundation of both the novel and the movie, the film adaptation adds a level of intimacy that they never reach in the printed version. In the book, Starr and Khalil only reminisce about their childhood friendship with Natasha in the car and discuss why he's supporting his grandmother. In the movie, the conversation in the car is much more romantic and the two even share a kiss. When Starr tells Khalil she has a boyfriend, he admits he knew that but promises he'll wait for her.
Subsequently, the reason the officer shoots Khalil differs between the book and movie. In the book, Khalil begins to open the car door because he's worried about Starr. Khalil reaches into the car to grab a brush and uses it before being shot in the film.