titanic_charlie, are you talking about that car?

If so, have you seen the "Ghosts of the Abyss" extended version?

Cameron went into the cargo holds and for a moment he thought he saw it in an almost unrecognizable pile of debris. He thought he saw either a tire or fender, or maybe even a headlight. However, due to the silt and low visability of the hold, they could not possibly identify it.

From what I have read, the car would be totally deteriorated due to its thin metal plating.