The more things change the more some have to stay the same.
This design element is considered a BMW trademark. Though photos are not taken from the same angle, I have highlighted the rear window curve. This contour has remained the same since the early 80's even earlier for some models. It is carefully considered and maintained as well as thought to be attractive. even under the auspices of revolutionary stages of the company's design.
Seems successful car brands have a family of their own complete with siblings. So, what makes 1 car hot and 1 car not. Maybe we can do a slide tweaking a car to fit into those two categories. I think Michelangelo said that all good art/architecture is based on human proportions, more examples to come on that thought.
