I've come across the following sentence:
El de mi hermano también.
My brother, too.
What purpose is served by "el de"? Why not simply say:
Mi hermano también.
UPDATE: The above example is missing some context, but I was too unfamiliar with Spanish to realize it until RSanchez posted an answer.
The missing context is that there is a conversation between two individuals:
Person1: Mi coche es viejo.
Person2: El de mi hermano también.