While waiting for a mechanic, a prize fighting luchador is forced to defend his broken down van from a wild chupacabra.

For what it's worth, I'm hooked and would buy a ticket today if I had the chance.

The above points out an interesting issue though - the stakes need to be higher than defending the van. Couldn't he just run away? What's IN the van that he's trying to protect? (FAMILY?)

Interesting character. Interesting antagonist. Potentially interesting situation.

But the "while waiting for a mechanic" is incidental rather than casual. Of all the muchos luchadores in Mexico, why does the chupacabra attack this one? And what is ultimately at stake has to be more than a broken down van -- doesn't it?

A luchador is a Mexican wrestler, they're known for wearing masks.
A Chupacabra is a Central/North American mythical creature, sort of like a Yeti or Bigfoot.