Freeway
(1996)

Vanessa (Reese Witherspoon) eventually makes it to her grandma's house, only to discover her dead.  Wolverton (Kiefer Sutherland) arrived first, and strangled her to death.  A struggle ensues, in which Vanessa manages to kill Wolverton in self-defense.

Seconds later, Detectives Wallace (Dan Hedaya) and Breer (Wolfgang Bodison), who were hot on their trails, arrive at the scene, and realize what happened.  When they ask Vanessa if she's alright, she answers, with an expression that mixed alienation, sadness and a bitter smile: "You guys got a smoke?!"...And the movie ends.

 Thanks Dr. Mat; who also adds: "...this was one of Reese Witherspoon's finest performances in her career."