The A8 has aluminum at its core, and weighs as little as 4,400 pounds. That makes it one of the lighter luxury four-doors-believe it or not-and it gives it a more nimble feel than its rivals.
This year, a set of new powertrains ratchets performance up and betters gas mileage. In the order of number of cylinders and output, the engines now rank from a supercharged six, to a pair of twin-turbo V-8s, to the carryover W-12. Each has a distinct mission in mind, and we have our favorites, for sure.
The 3.0T gives Audi more reach at the bottom end of the A8 lineup. It gets its power from a 3.0-liter supercharged six-cylinder that nets 333 hp and 325 lb-ft of torque. As the entry-level replacement engine for the former 4.2-liter V-8, it's a flexible powerplant with more muted response than we've heard from it in other Audis--and it's still capable of 0-60 mph times pegged at 5.5 seconds, and a top speed of 130 mph. All things considered, those are reasonable figures at its price.
A more gripping option is a new twin-turbo 4.0-liter V-8. The base version rates at 420 hp and 444 lb-ft of torque, and pushes the sedan to 60 mph in 4.7 seconds. That's much better-until you consider the high-tune S8 and its 520-hp version of the same engine. With that configuration the S8 drops the 60-mph run in 3.9 sec and hits a top end of 155 mph. The only thing the S8 doesn't do better is space: it's only offered in the short-wheelbase body.
At the ethereal W-12 level, the 6.3-liter engine pours out 500 hp and a waterfall of 488 lb-ft of torque. It hits 60 mph in 4.4 seconds and a top speed of 130 mph. We've spent the least time with this powertrain, but have driven related iterations of it extensively in other sedans and coupes. We'd predict its appeal goes deeper than the 12-cylinder badges, but we'd probably cut that corner if it were spending money on our own fleet.
All A8 sedans sport an 8-speed automatic transmission that's sure to become an industry standard. The calibration is perfect. The 8-speed smoothly engages the perfect gear every time. In the A8 it nudges the sedan to 29-mpg fuel-economy highs. It's an early gear-changer in Auto and Comfort modes; in Sport or with a heavy right foot, it'll snap off gearchanges quicker than you can flap the steering-wheel-mounted paddle controls.
Audi's all-wheel-drive system gives the A8 a sure-footed sense of the road. The system doles out torque with a 40:60 rear bias, but can flip that script if the front wheels have more traction. S8 sedans have a rear sport differential that can move power from left to right, and vice versa. The same device can be had on a Sport plus package, where it's bundled with summer tires, dynamic steering, and air dampers.
All these options give the A8 extraordinary range. A base A8 3.0T with all-season treads can come off the same configurator as a W12 with summer tires, or an S8 riding on 21-inchers.
That's where Drive Select comes in, to impose some logic on all the adaptive systems and configurations. Drive Select acts as a godhead for the adjustable steering, suspension, transmission, and throttle. With a click of a switch, drivers can choose from comfort to sport modes or come up with a custom configuration. It hasn't been as successful in other models, but the A8 it helps the car get a better sense of mechanical coordination.
Among all the models, the S8 is an easy favorite. It's too heavy and long to be a pure athlete, but against a big 7-Series or S-Class, it feels positively youthful. There's enough ride compliance and body lean to leave its luxury credentials in place, but it's also perfectly happy to lead the charge off an exit ramp at a hundred-mile-per-hour clip.