h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

I know I'm not the only one here who has been trying to piece the whole thing together. Like I've read, this movie leaves you with more questions than answers. I find myself going from one webpage to the next looking for clues, answers, anything I can use to piece it all together. Consumed by curiousity, I am wondering if the Blair Witch has not possessed us all.
Has anyone considered the evidence with the photos of Josh's car.
In the backseat there appears to be a backpack, and a flannel shirt.
Could these have been Josh's? Could he have returned to the car after
they had been initially lost? If the flannel shirt in the bundle of sticks was indeed Josh's, could it have been only a partial piece of the clothing. The strips that tied the bundle did not appear large, and the inner contents could very well have been perhaps a sleeve.The contents of the bundle could have been that of an animal's?

All of those thoughts are quite plausible. The one question that keeps repeating for me when I see evidence and clues is, "what's the motivation?" If Josh was able to return to the car, why did he leave it there? Why did he leave the backpack there? Why was there no signs of blood, provided the contents of the bundle were in fact Josh's?

There is no real way of knowing what happened next after the film is over. It's all a matter of choice on your part. What do you think. What works for you? The film leaves much open to interpretation and each individual will experience that a bit differently.