Check out the badass trailer, then watch the movie, it's well worth it. It is a film adaptation of a French book called The Wages of Fear. (There is a famous French movie adaptation of that book as well) http://www.youtube.com/watch?v=UMof5PuQF7w
It was one of the most expensive movies of it's time, but failed miserably because of bad marketing. People were expecting another Exorcist (especially with the name Sorcerer), not a dark jungle adventure thriller.