There is a sort of mysticism to what you don't, or can't rather, have. I always felt that with the models or body styles of cars made in Europe, BMWs especially. Think of cars like the Audi RS2, any M5 Touring, etc.
I think for me, it would have to be the 1 series hatchbacks. The E81/E87 chassis designations in particular, the first generation. I think a E81 135is would be one of the coolest BMW cars made. Or even a 1M hatch. They would have almost been able to make it a 10 year anniversary of the Z3M clownshoe when the 1M was launched.