Tested: 2021 Mercedes-Benz S580 Resets the Flagship

UPDATE 9/13/21: This review has been updated with test results.

CORRECTION 6/22/21: This story has been updated to correctly state the specifications of the S500's six-cylinder engine. Also, the AMG Line option does not include 21-inch wheels, as previously stated.

It might have been the moment we were choosing between the Mobilizing massage or the Classic massage, but we missed a turn. A new S-class brings with it a ton of new tech, and we were so busy playing with all of it that we ignored the navigation system directing us to the Jersey Turnpike and the George Washington Bridge. The new route took us through the Holland Tunnel, landing us in Tribeca. After driving the length of Manhattan, through the Bronx, and into Westchester County, we arrived in Connecticut to rejoin the prescribed drive route.

Along our improvised route, we passed multimillion-dollar lofts, high-rent apartment buildings, and suburban estates with lawns that must take weeks to mow. The S-class is exactly the kind of automobile you expect to see purring along these roads. Act like you belong, the adage goes. The latest version of Mercedes's flagship sedan makes you feel like you do.

There will undoubtedly be AMG-tuned versions, but for now U.S. shoppers can choose between a 429-hp turbo- and supercharged 3.0-liter inline-six in the S500 and a 496-hp twin-turbo V-8 in the S580. Both are equipped with 4Matic all-wheel drive. Under foot, the 496-hp V-8 seemed a bit sluggish at first, but then we hit the Dynamic button on the large central display. The darn thing was set to Eco mode, which attenuates your most immature wants with gas-saving reluctance. We skipped over the other options and went straight to Sport Plus, which lowers the body height 0.7 inch, increases steering effort, alters shift points, spruces up the engine response with a livelier throttle map, and engages a less intrusive stability-control program. A 48-volt electric motor eliminates delivery delay of those abundant horses, contributing as much as 184 lb-feet of torque to the 516-lb-foot peak as well as 21 extra horsepower for short bursts. We liked Sport Plus, and the change revealed the sports sedan hiding in this sedate cruiser. Let it rip and 60 mph comes up in 3.9 seconds, with the quarter-mile passing in 12.5 seconds at 114 mph. Like the last two generations of the S-class, the seat bolsters get into the act by inflating and deflating to counteract cornering forces, a reassuring "I got you" from the car if you choose to engage the dynamic seat mode.

On less exciting roads, we took advantage of the car's semi-autonomous driving function. By letting the S-class deal with the exigencies of traffic, we were able to fully explore the 10 massage experiences, the cloud-soft headrests, and the $6730 30-speaker Burmester audio system's 1750 watts, including the in-seat resonators that deliver the bass to your backside. Taking it easy also resulted in a decent 20-mpg fuel-economy average—spot on with the S580’s EPA combined estimate—as well as a frugal 32-mpg return on our 75-mph highway test, beating its federal rating by a big 7 mpg.