I really like this piece. But first, let me get a few things straight, just to make sure I'm understanding correctly.
The gist of what I understood from this was that the girl was outside a club on a roof and fell. Either that, or she was outside a club and walked out onto the street and got hit by a car. Actually, I'm going with the second one. Did I get that right?
As for the actual writing, I like your use of disconnected sentences (don't know if I used the right word or not). Because they weren't compounded together, it gave the story a sort of staccato effect, like the main character's thoughts corresponded to her heartbeat or something. (Did that even make sense?) Your grammar is actually really good, except in dialogue. I could try explaining what needs to be fixed, but you could probably look that up (and it will probably make more sense that way).
Other than the slight confusion and the dialogue (even though there isn't really anyone else talking), I really like this. Your take on someone's last moments before death was really intriguing. If you ever decide to expand on this, let me know so I can read it! (But don't feel like you have to write more about this, either. I always love a good short story.)