My parents never knew about her.
She lived in my room, in my closet, behind the pile of stuffed animals that I had collected since I was tiny. She was tiny too. She wore an old dress and no shoes. She had dark hair and light eyes. I found her on my ninth birthday.
I called her Shadow. It was the same name as a cat I once had.
The cat had been sleeping on my Dad’s car's warm engine. No one knew until my Dad started the car to go to work. Then the little black cat became even smaller pieces of red and mushy bits all over the inside of the hood. I was standing on the brick driveway when it happened. A bit of fur hit my face and stuck there. My Daddy screamed. He was crying. I didn’t see what all the fuss was about. It was just a darn cat.

I think I'd drop the "warm" before "engine".

I'd keep it at one line and get back to the story at hand.

We get a preview of the speculative right away.
The voice was working
then the backstory about the cat.
It isn't a story about the cat.

Like this:
"I named her after a cat I once had. Poor thing got killed under my dads car. But shadow is special. She gets me."

The problem I had with this was the abrupt shift in focus. I'm interested in this girl in a closet and then you suddenly go off about the cat. This almost looks like you have the opening to two completely different stories.

"Then the little black cat became even smaller pieces of red..." This is passive, and does not create as much interest as it could. Get the senses involved - hearing the wail of the cat as it is being chewed up for instance.

I'm curious as to how a bit of fur hit the boy in the face. I'm assuming the hood was down, in which case this would be impossible. If it was up, then how did the cat get splattered all over the inside of the hood?

I agree with the comments posted above me, regarding the shift in focus from the mysterious girl, to the deceased feline. However, that said, my interest was definately piqued, and I'd read on; I liked the style and language of the opening few lines. If you want someone to review the whole thing, I'd be happy to.

Cheers,