that works good but i didn't mean using prewritten code objects sprites and collision fields witch all pretty much still use ridged body physics witch work good with most arcade racing games.
lets say we are developing a game witch will be published as a flash game with unity witch down the road i would modify it to work as a 50.000 KB swiff file. (i am not looking foreword to that and i know already it might not work)
1 . i would start with a blend file of a door
2 . i would mark all the flex points and nodes by subdividing the door
3 . import the pictures to use a textures and apply them along with lighting and code
4 . export the door to a collada file
5 . import the the file and all of the graphics and code
6 . put the door and the rest of the imported car parts together with unity this is the way for this to work if you want to hit the wall and there be plenty of flying steel
yes i know this is way to over complicated
but in the end it is worth it
i might be doing something wrong but this is only a hobby and i have to much to do