Living in California, you must have experienced wildfires yourself, it's quite a dark picture you paint here! I have never been close to one, does the fire really spread so fast? It seems a bit unrealistic.
I like the ending of your short story, because I think it is very probably something like this will happen. Somewhere else in the world if not in California.
Something I was missing was some emotion from Micheal towards his dying/death girlfriend, and a more detailed description of how the fire is closing in on them.
One detail I especially liked was that the truck’s gas gauge had been stuck on E for years, that made the story vivid.
Overall, I thought the set up of your story was very interesting, because I can see it happening in real life even though it shouldn't.