It includes a hybrid system hidden in its powertrain that undetectably assists with power and efficiency on all forthcoming engine variants. (Highway estimates reach almost 30 mpg.) There’s a novel active suspension system that replaces the traditional anti-roll bar with adaptive dampers and special air springs. It offers four-wheel steering so light it brought to mind the image of Fantasia’s ballerina hippos when I test-drove the 4,751-pound car.

I was surprised, for instance, when during a late swerve to merge into a lane exiting the FDR on Manhattan’s East Side, the car actively worked against me. I tried to accelerate and zig left; it abruptly braked and forced the steering wheel to zag right. The car’s decision to counteract all of my driving inputs made a dangerous situation out of what was otherwise a mild enough maneuver to incur zero honks of protest, even in New York’s legendarily aggressive rush hour.

Suddenly, being inside the car felt like combating an alien presence. Rather than the rare ecstasy of when a machine and a human mind seem to merge for perfect driving engagement, it felt like the car rejected me altogether.

This was the first time something like this has happened in my 15 years of testing and reviewing automobiles. It wasn’t a good feeling.

An argument can be made that because the A8 isn’t meant to be driven like a sports car, my maneuver was not in configuration with its intended use. But even the most sedate bosses, and especially the most powerful ones, will need a driver capable of making that type of move, and others. Mr. Chauffeur will not want to have to fight against Audi pre-sense, the carmaker’s standard automatic emergency braking system, to do it.

Then again, whether this all matters largely depends on where you sit, both literally in the car and figuratively regarding the future of driving.

For instance, the 2019 A8 performs like you would imagine with its 335-horsepower V-6 engine and eight-speed automatic transmission. It’s smooth, solid, and persistent on the gas and brake, with capable if nondescript handling. It feels like the computer does everything for you; in this sort of car, that’s typically the point—ninety-nine percent of the time you’ll be riding in executive mode rather than action mode, anyway.

Riding is the key word: Get most anyone in the back seat and they’re unlikely to comment on or care about the powertrain, suspension, or how tight the steering is. Whether or not the driver has activated the Level 3 autonomous driving, a system that Audi is calling Traffic Jam Pilot, may hardly be noticed. (For now, it’s a feature unlikely to be installed in any A8s sold in the U.S., because the technology violates laws in most states.)

Instead, they’ll ask about the foot massages and admire the mood lighting. They’ll comment on the air ionizer and the churchlike quiet of the cabin. They’ll want to use the flatscreens and heated seats. This is as it should be—the advances of today’s cars allow us to use and appreciate them without having to know or even care about the inner workings of the chassis.

“This is the nicest car I have ever been in,” said Evan Ortiz, Bloomberg’s photo editor, as I drove him and our food critic, Kate Krader, home one evening. I wanted to get some non-car people inside the A8 to give me some feedback. “It feels very special, like a sense of occasion,” Krader gushed.

Large luxury sedans are difficult to write about because, at this point in the history of modern automotive manufacturing, they’re all very good. They all offer big-engine, long-wheelbase versions with supple leather massaging seats; crystal-clear heads-up and crash-avoidance displays; and perks such as air purifiers, fragrance disseminators, and extensive rear-seat entertainment systems that are on par with private theaters.

Choosing the best one for you is often more about brand loyalty and marketing than it is about one car being better than another.

And in the scheme of things, that’s really where Audi AG’s latest—the biggest car in its line, and the fourth generation of its star—is now. It’s special because it represents the Ingolstadt, Germany-based automaker’s shot at competing directly against the exceptional and heretofore dominant town cars from BMW and Mercedes, the $83,650 7 Series and $91,250 S-Class, respectively.

The Mythos black A8 that I drove cost $102,000. (That figure includes the $83,800 base price and some serious executive-style upgrades, which I’ll dissect in a moment.) Others from BMW AG and Mercedes-Benz AG routinely cost mid-six figures as you get into the “executive-level” packages that offer extra room, foldout working tables, extra rear-seat controls, and the like. The 2019 A8 feels less like the coach-built interior of a private jet and more like the inside of an intimate office or control room. Four-zone climate control, leather detailing, LED lighting, two large sunroofs, and a rearview camera come standard, as does the center-placed rear-seat console full of knobs to control climate, audio, and entertainment settings

As the third party in what’s largely been a binary race for luxury sedan preeminence, Audi’s A8 offers consumers what’s often a welcome out from the stranglehold they may feel choosing between the two brands that have owned the segment for decades.