I can answer questions related to the BMW e30. These are the cars produced from 1984-1991 (1992 for convertable) in the United states. I am more fluent with the six cylinder models, although few things changed for the 4 cylinder cars. I know most of the problematic areas of these cars, and have found ways to fix them.
I have owned six different E30's over the last 10 years. I do all my own work, and know about ever nut and bolt on these cars.
BMW Car Club of America