Damn I love E30's. Some nice and subtle modifications. The hood should open the other way like it did on the older BMW's. Also you have to add some reflections/highlights to the glass of the headlights to make it look realistic.
You did a okay job on the roll cage. A lot better than my first brushed one. have a look at
THIS tutorial. It'll show you the shadows and highlights you're missing.
A good tip is when doing a fully brushed roll cage start with a completely removed interior. Like when you're changing the background it's usually a good idea to completely redo the inside of the car. Also study a roll cage before you do so, some of your pipes don't make sense.