I'm having trouble believing that one person can accomplish this in 12 days with few tools could disassemble a car and build something even remotely drive-able without a welding torch, engine jack, and countless other tools. Was he stranded in the desert in the way that I imagine?(no water, sand dunes everywhere) Or did he end up in some desert town that had basic facilities for him to do this type of work?

Even the most skilled machinist would have a tough time doing this. Seems implausible.