No, this isn't about speed. We all know who would win that one. This is about overall ride, comfort and day-to-day driveability.
Drove around in my buddies 2000 Vette yesterday and walked away with the following impressions.
The car is loud. The engine, the exhaust...plain loud.
The car is "clunky". Close the doors...clunk. Go over a bump. Somewhere in the chassis you hear a clunk.
The interior, while having some nice features (heads up display), is rather stark.
The car is powerful. No doubt about it, if it's American muscle you're looking for, the 'Vette has got to be #1.
After the drive, I got into my IS. Closed the door and heard the satisfying "thunk". Started the car, turned on the stereo, and opened up the moonroof. As I accelerated through the first curve, I knew which car I would take anyday, given the choice.
Long live the IS.