When chopping up the body never use the Delete button, use detach and then select the detached part and delete it. That way you wont get ****ed up smoothing groups, like on the windscreen.
Right, I've remade the whole project from the beginning... I think it's better than the previous one. Oh, abuse the reflection on the dashboard and the windshield (2nd pic)... I haven't checked it, I wanted to see the car itself if it has problems, I didn't care about the nasty reflections...
Looking pretty good already, must have taken hours to make all those textures. Roof looks little too dark, garage is well lit and more light should bounce back from floor. Little bit dirt on fridge and door would be good too, working all day at the garage will get your hands dirty and everything you touch with them