This is the coupe, not the sedan, but look at this Fifth Gear video with Vicki ...
(Sorry, I can't seem to get the YouTube embed to work.)
It seems that most consider the sedan a pig compared to the coupe. Not so. When optioned out I think the sedan is only 20 lbs heavier. It's certainly true that one sedan can be just as light, even lighter than a coupe, depending on options. So, I can see getting into a "lightweight" (again, a relative term when talking about E9x M3s) sedan. If it's anything like the coupe GTS then I'm all for it, assuming it comes to the US.
Cheers.