Many people know of the Impala, the Metallicar. What they don't know is that the Metallicar is conscious, sentient.
No one knows how this came to be. Many have speculated, but there are four main theories.
1. It was the work of the archangel Gabriel. Why, you ask? I don't know, he probably just didn't have enough work to do. But then, does he ever?
2. The car isn't a car. It's a supernatural shapeshifter that took a shine to our boys. That's even stranger.
3. A witch.
4. It's a theory that belief creates, or at least strengthens some objects. With the Winchesters, and all those people that think it's bloody awesome…
These theories all have two things in common. They explain the observable evidence, and they are all completely false.
Meanwhile, the Impala grins to itself and sends a telepathic Merry Christmas! to Chuck.