If you're just looking to add the rings to your garage, there's an affordable base A6 for you. However, those looking for a performance car can find it–with three more interesting options from which to choose
The S6 is the monster of the group. With a 420-horsepower, 4.0-liter twin-turbocharged V-8, a seven-speed dual-clutch transmission, a sport suspension, upgraded brakes, and an available torque-vectoring sport differential, the S6 offers a 0-60 mph time of about 4.5 seconds, as well as more satisfying handling, all without giving up much comfort to its big 21-inch wheels and optional summer tires.
The other flavors of the A6 are also strikingly fast performers that don't sacrifice that much efficiency. The mid-line option is a gasoline-powered 3.0-liter V-6, with supercharging and direct injection. By the numbers, this V-6 blasts out 310 hp and 325 lb-ft of torque, all harnessed to the eight-speed automatic and all-wheel drive with a rear torque bias of 40:60. Audi says it's good for 0-60 mph times of 5.4 seconds, and the same governed top speed of 130 mph. It's slightly more refined in feel than the TDI, but by so little it's a difficult justification.
The mostly passion-free standard Audi A6 pairs a continuously variable transmission with a turbocharged 2.0-liter four-cylinder with 220 horsepower. It's a combo rendered more sedate by the A6's size and weight--even more so with the optional all-wheel drive, which at least adopts an eight-speed automatic instead of the CVT. It's not slow, with 0-60 mph times in the 7.5-second range, but it's a less convincing example of luxury in context here, especially with the CVT, which takes away some of what we love so much about the turbo four.
As for that base 2.0T/CVT powertrain, it's confident enough; and while previous versions generated a drawn-out drone, this latest version instead seems to try more to mimic a conventional automatic transmission, albeit with slurred steps. A sport mode and steering-wheel paddle-shifters help, somewhat, although we much prefer the sharper eight-speed automatic transmission and quattro, a combination that's smooth and surprisingly quick.
We'd be much more pleased to pay the premium up front for Audi's excellent new turbodiesel 240-hp 3.0-liter six. Its powerband is much narrower, and there's just a little more noise and vibration, but the payoffs are many. Performance through standard all-wheel drive and an eight-speed automatic is smart: 0-60 mph happens in about 5.5 seconds, thanks to 428 pound-feet of torque. Fuel economy is outrageous, at 24/38 mpg, or 29 mpg combined. The A6 TDI is better equipped, too, and isn't caught in the features and size limbo that the base A6 can be, compared with a high-end A4.
With either the supercharged or the TDI powertrain, the A6 is a joy to drive. It jumps off the line, tracks cleanly and without torque steer. The eight-speed automatic is a perfect fit, clipping off upshifts and downshifts with just an occasional part-throttle moment of confusion. And the transmission seems always fully prepared to make your choices with the steering-wheel paddle shifters just as seamless.
All A6 and S6 models get Audi Drive Select, a sometimes-frustrating system that adjusts the feel and response of the transmission, throttle and steering to Comfort, Auto, Sport and individually tailored specs. We've found issue with the execution of Sport steering mode, which feels too heavy, and Auto can deliver too much weight in high-speed sweepers. The A6 handles well, and even though its all-wheel-drive system is biased to the rear it still tends toward understeer. With impressively strong brakes and Sport settings, it's nevertheless enjoyable in tight mountain curves.