How does the 2009 Audi A6 compare to its competition?

Audi’s full-size A6 competes with cars like the Mercedes-Benz E-Class, Infiniti M and BMW 5 Series, which all start in the $45,000-$55,000 range. Cars.com editor Kelsey Mays reviewed the 2009 A6 with its new supercharged V-6 engine, and he addresses how Audi fares against its fiercest rivals in his full-length review, found here.
Mays found performance issues (specifically throttle lag) with the A6 in this configuration, and says that this flaw, combined with the A6’s touchy brakes and wind noise, gives competitors the edge:
“Behind the E-Class and 5 Series, the A6 is one of the most popular cars in its segment. I have a hard time understanding why, considering Infiniti has a compelling alternative in the M, Jaguar has the XF and Lexus has the GS. If you're doling out this much money, a car ought to be free of drivetrain issues like those the A6 suffers. Give the A6 an honest workout on your test drive, and if you really find no fault with the driving experience — accelerator lag, touchy brakes, highway wind noise or otherwise — then perhaps its strengths deserve a closer look. I can't summon enough enthusiasm to overlook such issues, and for 50 large, there are plenty of competitors with serious strengths and fewer compromises. Audi has a contender in the A4, but the A6 still needs some work.”