Great...until they brought in the chick....

I've always enjoyed the film. I just got done watching it after many years. I do agree with you somewhat though, I think it was rather unnecessary.

In Venna's defense, or more accurate the director's defense, it's hard to keep the viewers in suspense at the last part of thriller-type films. The chemistry between the characters is an essential part of any thriller. I agree with you that the entry of a third character destroyed the delicate dynamics between the brothers.

The director was succeeded to make us feel empathy for the brothers and feel together with them the fear, anxiety and terror they felt during the long journey in the middle of nowhere. The director erred in deciding to change the direction of "drive" and lead us to a completely different route that is no longer centered around the two brothers alone. And this road wasn't great as the first one. This is the main reason for the disappointment we feel.

Last note, I watched some similar movies before, It's all about minimilizm. Too many main characters & complex script with too many plot lines can ruin the film, at least parts of the movie.