A great message, in a funny way.
Given the fact that this is a road safety message, you have portrayed it well, but at the same time in a humorous way. My initial thoughts on this was that it doesn't hold a very strong message due to the fact that it IS funny instead of serious. The main reason for this is that car accidents aren't funny, although this could be just years of messages biased a negative and serious way talking.
The overall animation was done well, you have put effort into little details to make the movie better illustrated. Also the car interior was drawn with enough detail that you could see exactly what was going on, which was a great plus in your case. I loved how the noose come down in that suicidal song too.
There were a few things that got me though, more on a real world type of view.
Firstly the window on the inside of the car, the front one especially you had drawn with a series of straight lines. I don't know if this was intentional or not but it would have looked much better drawn with a single curved line. Again a lot of the other pieces of the car interior were drawn with straight lines, again they would have all benefited. Also another little note on the front drivers window, it wasn't really stretching as far forward as one in any car would, just a little something I picked up on.
Secondly, when he turns up the volume he turns it to the left. Personally I have never seen a system, in any circumstances from household amps to PA amps or car audio where the volume goes up when the knob is turned to the left. So that little issue kind of bugged me a bit as it would have been just as easy to animate it the other way.
Thirdly, when he steps out of the car initially he is on the passenger side of the car (being Britain). I understand he could have walked to that side but the way his reaction come up and the way he was standing next to the engine bay signified he had just stepped out.
Those are just a few that really stuck out at me. Overall the movie and animation was good but I would just make sure of little things like that in the future as they can really put a negative spin on a movie.