The M5 makes the same tradeoffs but in a different way. It takes a very good sedan and makes it even better. But, there's no question that it would be even better to drive if it wasn't limited to being able to comfortable seat 5 people or fit golf clubs. We might still even have a lovely NA motor like in the E60 =[
Also I don't think the M5 is actually a sports car? I mean don't get me wrong, it's completely awesome and I would absolutely love to have one, but it's also nearly 4400 pounds and a sedan.
Origins of the term "sports car": http://www.roadandtrack.com/car-culture/a28225/sports-car-de...