Well, My family gave my truck its name, the Batmobile(84 4runner, flat black everything). I don't like that name, I usually just refer to it as the heap, or the brick. About to camouflage it in hopes of killing the batmobile name forever.
Why we name them though, I know for me it is a case of having to many trucks. I would rather tell some one I am going to town in the Heap, or Red rather than just the model of the truck I am taking that day. Gives more of a since of attachment to the truck