A8 and A8 L are powered by a 310-horsepower 4.2-liter dohc V8, driving all four wheels through a five-speed Tiptronic automatic transmission. The A8 packs all the luxury features you'd expect for its price, and rides on a wheelbase of 113.4 inches, comparable to that of a modern, full-size U.S. sedan.

A8 L is stretched out over a limousine-like wheelbase of 118.5 inches, for more rear-seat leg and headroom. Xenon headlights, heated seats front and rear, a ski sack, rear-compartment sunshades and a heated steering wheel are standard on A8 L, and are part of a $2,550 Premium Package for the A8.

S8 is propelled by a stouter version of the same 4.2-liter V8, producing 360 horsepower. Hotter cams, a two-stage variable intake manifold and a less-restrictive exhaust perform this trick, while at the same time upping torque to 317 pound-feet at 3400 rpm (from the A8's 302 pound-feet at 3000. The S8 can flash from zero to 60 in 6.3 seconds, and dispatch a quarter-mile in 13.9.

Backstopping that added speed are huge ventilated disc brakes, 13.6 inches front and 11.0 inches rear, with four-piston aluminum Brembo front brake calipers. The S8 suspension rides nearly and inch lower in front, its springs and shocks are about 30 percent firmer, its stabilizer bars are thicker, and its five-spoke, 18-inch alloy wheels carry 245/45ZR18 performance tires. The S8 shares its 113.4-inch wheelbase with the A8.