The new 550's are damn nice. I HAVE driven one, even thought it's not for sale, or at dealerships yet!! They are very quick, noticibly quicker than the 45's (havn't driven a 545, but have a 645, same thing). I have no doubt the GTO could still beat it, but for what it is, the 550 is a damned nice car that I wouldn't mind owning. I love working on the newer E60's, and it's funny how the more I work on these BMW's, the more I want one, but not as much as I want a GTO. BTW, I am a BMW Certified Diagnostic Technician.