Not an uncommon thing to happen.
So far, doesn't sound demonic. The nice thing about the Catholic church is that many of them understand there are supernatural beings that are neither angels nor demons. Not necessarily all of the clergy, but those who deal extensively with theology or actually have training in exorcism. So far, if I were to assume this is all a product of your own mind, I would assume schizophrenia, or a very intense form of DID. It's not unknown for seperate identities to be aware of each other. Usually, however, a secondary personality forms in response to some sort of trauma, and takes on a protector role.
However, so far, I personally think DID is not an accurate depiction of it, and I think my original classification as a fae-like entity is close. A lot of the stories of fae are very similar to stories involving UFOs and BFMs, which have been known to do weird things around vehicles.
Have you noticed any unusual electrical activity when he was around? Lights flickering, engines stopping, etc?