My God is this car stunning - especially in grey with red leather. The engine sounds great too, even if it's a little muffled. I do have a few gripes, though - first, the fact that the glass sunroof doesn't open is a deal-breaker for me. Yeah, it tilts, but it doesn't slide, and that's just a big tease. Secondly, the electronic throttle calibration is awful - and by that I mean even worse than Audi's usual eGas. It's damn near impossible to shift the S5 smoothly, and moving off from a start slowly is, well, just forget about it. As you start to slip the clutch at, say, 1000 rpm to move off the line, you can actually hear and feel the computer opening the throttles to give you a little assistance. The problem is that it gives you a LOT of assistance - so the car lurches forward. Then, once the computer realizes that the clutch has been successfully engaged, it pulls back that additional throttle, and you stop accelerating. I think Audi's trying to mask the fact that the 4.2-liter V-8 actually has very little torque at idle speed, and is easy to stall. I say "tough-let the driver figure it out on his/her own... it's better than having the computer screw up all your launches."
With that said, the Bang & Olufsen stereo is mind-blowing - and such a bargain, compared to the one in the S8. I'd kill to have a stereo like this in my personal cars. Or my house. Or half the nightclubs I go to.
And speaking of kicking it - the Quattro system will actually route some power to the rear on low-speed stuff, so you can actually kick the S5 sideways if you give full throttle when making a U-Turn, for example. If only it would do the same at higher speeds, too.