Wasn't real bad.
I'm not sure exactly what you were trying to accomplish...unless it's the obvious.
I'm not a stickler for graphics, ...i mean look at all the damn stick figure games and movies on Newgrounds...but, I have to say there were times where the movie sort of struggled from frame to frame (choppy play). I know nothing of flash, so I don't know how to be helpful here besides pointing it out.
With that said, I think it best to point out how short it was, first off. Even if the graphics and choppiness were taken care of more, it needs to be extended. Add more mishaps to cross the path of your main character. Perhaps add some dialogue and/or background for him. But please be original...don't use the long played-out plot points of the driver being all doped up on something or drunk or just completely stupid. That's too easy. I mean obviously the driver's an idiot...look at the 'slope' he drove down, then up, then backward.
Get rid of that reason-less mid-air explosion. Either tack on a good reason to make it explode or just cut it out entirely and finish off another way or add more beyond it.
Background music would have been nice too.
I didn't vote to blam it, I've seen much worse on newgrounds, I gave it a 2/5 in hopes that you were showing off progress on experimentation with coding with physics or something.
Overall it's bad, but not as bad as it could have been.
Good luck in the future. I'd like to see what you come up with next.