Bought an C5 A6 with a 4.2 and absolutly love it. It has 185,000 mi. and drives like it's just broken in. The only thing that took some getting used to is the slight lag when you first press the accelerator from a stop. It seems to lag just slightly. Does anyone have an explanation? Also on occasion, I take off from a stop and it feels as if the car is starving for fuel. You press the accelerator harder and it will suddenly take off. Any ideas? A few small problems... But oooohhh the power of the 4.2 is wonderfull.