Introduction

Audi A8's laurels are led by its aluminum space frame, stiff and light. It's a very refined sedan, a strong and sometimes favored contender against whatever Mercedes-Benz or BMW want to throw at them. A relatively dated product, its stylish contour keeps it looking fresh, even though 2018 is the last year of this generation, and brings no changes. 

An all-new A8 is coming for model year 2019. 

The A8's wheelbase is long, making a better ride and more room in the back. The high-performance Audi S8 uses a shorter wheelbase that used to be under the A8. 

Base engine is a supercharged 3.0-liter V6 making 333 horsepower and 325 pound-feet of torque. It's relatively thirsty, EPA-rated at 22 miles per gallon Combined. 

If want to get less fuel mileage than that, the 18-mpg engine is a twin-turbo 4.0-liter V8 making 450 horsepower and 444 pound-feet; that one brings a breathless zero-to-sixty time of 4.4 seconds. Both engines mate with an 8-speed automatic transmission and Quattro all-wheel drive. For extra chassis balance, there's an available dynamic handling package with sport rear differential. 

The Audi S8 slams 605 horsepower on you. It's a twin-turbo 4.0-liter V8 that adds 517 pound-feet of torque. Needless to say it brings a rousing road experience, especially strapped into the deep Valcona leather bucket seats, as you accelerate from zero to sixty in 3.7 seconds that will most certainly be startling. 

The S8 has LED lighting, 21-inch wheels, quad oval tailpipes, adaptive dampers and air springs. Its trunk is small for a full-size sedan, and rear leg space is limited by the short wheelbase. But it has 605 horsepower. 

Lineup

A8 L 3.0T ($82,500) has the supercharged V6 engine, Quattro all-wheel drive, leather upholstery, navigation, full-LED headlights, power front and rear seats, a sunroof, and power-closing trunk lid. Standard infotainment boasts satellite radio, Bluetooth phone and streaming, Bose speakers, and a USB port. Curiously, a rearview camera is optional, though parking sensors are standard. 

A8 L 4.0T ($92,000) features the twin-turbo 450-horsepower, 4.0-liter V8. 

S8 ($115,900) uses the shorter wheelbase and comes with a 605-horsepower V8. (Prices are MSRP and do not include destination charge.)

Numerous safety features include front knee and rear-side passenger airbags. Audi's Pre Sense system can tighten seatbelts before an impact occurs. Advanced safety technologies come in option groups, including adaptive cruise control with stop/go capability in traffic, blind-spot monitoring, lane-keeping assist, and Night Vision. 

Walkaround

The A8 is stylish, nothing flashy, not even excessive. It's sophisticated, restrained and low key. It's way less sleek and dramatic than the Audi A7 sedan. 

It's well detailed. Front LED lighting highlights the expansive elegance of the hood and shoulders. What used to be the Sport package of exterior tweaks is now standard, making it officially in our book a sport sedan. Never mind that the gearshift lever is patterned after the throttle of a yacht. 

The S8 is the ultimate sleeper, hiding its 605 horsepower under a hood and body that's no different than the A8 sedan, except four inches shorter, although it looks longer because it's lower. The subtle spoiler on the deck lid is the only cue. 

Interior

If the A8 exterior is well detailed, the cabin is extremely well detailed, with the best materials, whether it's leather, wood, aluminum, plastic, or splashes of chrome. It's plush and comfortable. The standard front seats adjust 18 ways, upholstered in perforated leather, and comfortable; it feels like two cushions, soft on top of a firmer one. At startup, tweeters rise from the dashboard, to name one cool detail. 

Two adults have plenty of room in the rear, comforted by individual climate control. An option includes a footrest for the right side and recline/massage for the left. The dual panel sunroof doesn't steal head space. Trunk space is 13.2 cubic feet, slim for a full-size car. The S8, with its shorter wheelbase, has a smaller trunk. 

Audi engineering keeps away almost all wind and road noise. The A8 is silent and serene. 

The standard infotainment system is impressive, using Audi's Multi-Media Interface, a knob on the console that spins and clicks, to scroll and select audio, phone, climate, and navigation. 

There are a couple flaws to the infotainment system. Some controls are duplicated needlessly, and voice control has a mind and voice of its own. It doesn't always respond properly to commands. Good luck if you can find one of those in life. 

Driving Impression

When you read the term lightweight aluminum chassis, it only means that aluminum weighs less than steel. It doesn't mean that the car is light. The A8 might be your best example (among very few), it comes out pretty porky, at 4670 pounds fully equipped. 

But the chassis and suspension engineers scored an ace, in making the A8 feel as light and nimble as a full-size car can feel. It's a complex suspension, which the Quattro system understands, to make the A8 feel sure-footed in corners. The front-to-rear torque split varies from 40/60 front/rear, to 60/40 front/rear. 

The supercharged 3.0-liter V6 engine is very responsive and has fabulous torque down low. It's not especially smooth, and can be noisy when the throttle is way down. Acceleration to 60 mph takes 5.5 seconds. 

The gearshifts in the 8-speed automatic are smooth, quick, well-spaced, and well-programmed, which is to say they come at the right times, so no invasive surges. In manual mode, the paddleshifters can be used. 

The 4.0-liter twin-turbocharged V8, with 450 horsepower, is basically the same engine as in the S8, with 605 horsepower. The difference is all in plumbing, breathing, and electronics. One thing that means is that the structure of the 4.0-liter engine is strong, strong enough to handle 30 percent more power without breaking. 

Drive Select can control the response of the engine, transmission, steering, and suspension. Comfort, Auto, or Dynamic mode can move the car from sedate to dramatic. In Comfort or Auto mode, the transmission tends to shift quite early, and it downshifts a lot. 

There's also an Individual mode, so an owner can find the overall setting for how he or she likes the car to feel. There's a lot of tweaking and awareness, to find that place. It's not unlike adjusting an 18-way power seat, it takes some experimenting and moving around. 

The S8 isn't a hotrod, not even with 605 horsepower and 517 pound-feet of torque. It's too smooth to be a hotrod. t. It's an executive uber-car. The ultimate full-size luxury car, with the ultimate motor. It's breathtaking in its power, and execution. With an 8-speed automatic, Quattro, adaptive dampers and air suspension, it's got it all. 

Summary

We like the excitement of the base engine, the supercharged 3.0-liter V6. Any A8 is well detailed, quiet, comfortable, and roomy–near the top of each category, compared to rivals the full-size luxury segment. The Quattro and 8-speed automatic flawlessly add to the dynamics. The S8 is a Master of the Universe kind of car. 

Sam Moses contributed to this review, with staff reports.