Too early to tell, I want to see these two in person before, I didn't like the look of the 645 until i saw a like 5 of them, then I liked it. Plus I give a thumbs down to the Rims. My vote goes to the M5 for now.
The M5 is way more agressive looking from the front. However, agressive doesn't mean better. I would say that the M6 looks better right now. I would have to see them both in person fisrt before I can be sure. Any word on wheter or not they will both be at the NAIAS?
The M6 is easily the better looking car overall, but the M5 does have a much more aggressive front treatment.
That type of power suits the M6 more... I just cannot see the M5 doing 205 mph with the kids in the back.