Earl Middleton, the protagonist, is the narrator of this text. He is a first-person objective narrator, which means that he is a participant in the story's events, and he is telling the story after those events have already taken place. You can tell because he uses past tense verbs to describe what he experienced. Typically, these narrators can be a little more reliable because they are not telling their story while the events are taking place, in the heat of the moment; they can be less emotional because they know how the story turns out. Because Earl is such a narrator, the fact that he ends the story without ever having made it to Florida—or even close to it—seems to indicate that he never did make it and that the optimism he felt at the time these events were taking place has long-since faded.
Earl's description of the gold mine near where their stolen car breaks down differs greatly now from what he thought then. Then "It seemed as if anyone could go in and take what they wanted" from the mine, but now he realizes that this "obviously wasn't true." Further, the mine seemed so close then, "huge and near, up against the cold sky," but he "knew now, [it] was a greater distance from [him] than it seemed[.]" At the time, he believed that he and Edna and Cheryl could reach the dream of a life he imagined in Florida, which seemed like a relative haven: a world away from Montana and the crimes he committed there. Edna didn't, though, so she plans to leave him.
Earl, by the story's end, is planning to steal another car, still not understanding, it seems, that he can never begin a new life or have that "fresh start" he longs for, just as he cannot get to Florida without stealing a car—or maybe at all. He can never reach that literal or figurative place, just as he can never reach the gold mine. His limited understanding is made all the more poignant as a result of his narrative perspective and the sense that Earl has lost the hopefulness that characterized him at the time.