I say ditch one of these 3series variants and give the fans a Z4 M-Coupe, instead of some Toyota/BMW concoction.
I understand that the reason for all these variants is it relatively cheap with modern production techniques and panel sharing/replication to create different models on the same platform. So for BMW they don't have to outlay a lot of R&D to create these variants. Makes business sense but definitely a lot of fans have been scoffing at the idea. My personal opinion is, long term, a lot of fans will be steered into other BMW models i.e. 1series or 5series or other brands, due to the similarity of design of the 5 types of "3" series you have. In all honesty, my opinion, commonness on the road causes a car to loose its appeal, no matter how good/fast it is. Lets count:-
3series sedan
4series coupe
4series convertible
3series GT
4series Gran Coupe
5 designs all of a similar nature. I'd choose none of them, as 5 years down the line, these will be common as Toyota Corolla on our roads.
BMW are milking a cash cow here to death...........