what was the motivation for abandoning the datsun, and why was the find of the car important

In October 1990, McCandless’s Datsun is found abandoned in the Mojave Desert by Bud Walsh, a National Park Service ranger. McCandless had driven it to the Lake Mead National Recreation Area in July, and against posted regulations, had driven it off road in the park and had pitched a campsite. A few days later, flash flooding almost washed away his campsite, and his car’s engine got so wet he couldn’t get it to start.

Because he wasn’t supposed to have driven off-road, he couldn’t get help from the rangers, and so he left the car with a note saying whoever can get the car to work can keep it. He uses this as another impetus to rid himself of unnecessary baggage, burning his money and leaving all of almost his belongings with the car.