That makes it tougher! a lot tougher! Your don't suppose it could be simmulated on a lift where you could be listening nearby? ie isolate the noise right to left. Do you know if the car has ever had any major front body work? Is there some kind of laser alignment check that could rule out something the eye can't see/ I'm thinking something obscure like a cracked weld covered by putty and paint. Maybe you need to get on a deeper knowledge discussion group like
www.bmwe30.net and ask questions. I have had my e30 for 18 years but I guess I have been lucky. I could also get the email of the NW e30 expert if you want. f