2014 Mercedes-Benz S550 Sedan Full Test

Where Engineering Trumps Discomfort

Published: 02/24/2014  - by Josh Jacquot, Senior Editor

Saying that the newly redesigned 2014 Mercedes-Benz S550 Sedan can drive itself is only occasionally an overstatement.

You see, using the big Benz's Distronic Plus with Steering Assist feature, we "drove" for five minutes and 43 seconds without touching a single control. This event, which occurred in typical Southern California slow-and-go traffic, broke not only our personal record for deferred prudence, but also our company's strict driving policy, which specifies that we never drive with less than one hand on the wheel.

Legal counsel cringed. Insurance actuaries cried. And somewhere in Germany a stoic Mercedes engineer leaned back, folded his arms and cracked a subtle-but-satisfied smile.

Arrival of the Self-Driving Car. Sort of
Cruise control set to 65 mph, the S550 loped along in sub-20-mph traffic, managing not only the gap to the vehicle in front but also the modest steering inputs required to maintain its lane on this straight stretch of overcrowded freeway.

And though we half expected to find a fairy godmother performing this magic, it's actually the product of a network of connected sensors including a multistage radar array and a stereo camera. In Mercedes-speak it's called Intelligent Drive. It can also apply the brakes autonomously (PreSafe Brake) to reduce an imminent collision or — by doing so on only one side (active lane keeping assist) — to prevent the car from leaving its lane. Most of these technologies come bundled together as part of the $2,800 Driver Assistance Package, which is, ironically, one of the least costly options fitted to this test car. Bibbidi bobbidi boo, indeed.

The Active Steering system, said one Mercedes official, doesn't ask for input below 17 mph. It simply looks at its surroundings and decides what to do: a disturbingly humanlike behavior matched by our equally disturbing near-immediate trust in a self-driving car.

Truth is, the system isn't designed for autonomous driving, and above 17 mph its label as an "assistant" becomes more honest. At freeway speeds performance more closely aligns with many of today's less-consistent electronic devices. We discovered it worked best on freeways with well-defined lane markers, where it could easily determine the preferred path and make subtle inputs. Remove your hands from the wheel completely at this speed and a graphic on the instrument panel will remind you to replace them in 10 or so seconds. Ignore that and the steering assistant disengages completely shortly thereafter.

"The system is designed to never be abrupt," said the Mercedes official. And it certainly isn't. Surprising, maybe, but not abrupt.

Occasionally, at lower speed, it locked onto the vehicle in front with Sidewinder-missile persistence. This, as you might imagine, led to some interesting moments. On one occasion, the six-figure sedan attempted an unexpected lane change in determined pursuit of a beer truck, prompting one editor to wonder aloud if possibly it was Miller time in Stuttgart.

Still Uses Pistons and Gasoline
Like the last-generation S-Class, this one is offered in only one wheelbase in the U.S., which makes it positively massive. But size is really just a state of mind in a car offering more amenities than a Napa Valley spa. Though overall length and wheelbase remain the same as last year's car, the new S-Class is 1.1 inches wider and 0.7 inch taller than before.

And despite many improbabilities, the S550 does have an engine. Under the hood is a twin-turbocharged, direct-injected 4.7-liter V8 lashed to a seven-speed automatic transmission with paddle shifters. Output is 449 horsepower at 5,250 rpm and 516 pound-feet of torque at 1,800 rpm, which is, well, plenty. Though our tester is rear-wheel drive, all-wheel drive is optional.

Hammer the big pedal and the 4,883-pound sedan squats, tucks its wings and rockets itself to a near-silent, wheelspin-free 4.9-second 0-60 time (subtract a 1-foot rollout as at a drag strip and the number is 4.6 seconds). The quarter-mile is gone in 13.1 seconds at 108.2 mph, a performance that lands the S squarely between Audi's 3.0-liter supercharged and 4.0-liter turbocharged A8s in terms of elapsed time.

Two modes (Sport and Economy) are available to customize the drivetrain to your liking. Though there's little point in a 2.5-ton sedan that makes its occupants aware of every millimeter of throttle travel, that's just what Sport mode will do should you select it. We spent our time in Economy mode, which offers more modest response appropriate for stately motoring.

There's also an "Eco" button, which activates an automatic stop-start feature. Despite its use, we measured only 16.8 mpg over 683 miles of mixed driving. The EPA rates the S550 at 20 mpg combined (17 city/25 highway).

Short of its ability to run with a Camaro SS in a straight line, it's not the acceleration that dominates the S550's character. No, rather, it's that the sober sedan is capable of such feats while imposing zero drama on its occupants.

Go Ahead, Hit a Few Speed Bumps
Possibly the biggest contributor to the S550's calm demeanor is its air-suspended, actively damped chassis. The suspension, which is driver adjustable over two modes (Sport and Comfort), utilizes the stereo camera in Comfort mode to scan the road ahead and adjust the suspension accordingly, an option Mercedes calls Magic Body Control ($4,450).

With so much technology leading the way, the S glides over freeway expansion joints with unruffled grace. The ride is both buttery-smooth and comfortably controlled.

Our tester was fitted with 19-inch five-spoke wheels as part of the $5,900 Sport Package, which also includes unique front and rear bumpers and side skirts. Though it's hardly an important measure of success in this category, the S is far more capable than it needs to be when driven quickly. Handling tests (65.6-mph slalom, 0.89g skid pad) don't bear out its demeanor when driven with purpose.

Cornering is flat thanks to the Benz's Active Body Control system. Though it requires time to adjust to a lack of body roll in a sedan this big, the control benefits are genuine enough to lead passengers to expressions of utter amazement. Despite the fact that every input is subject to electronic oversight, steering feel and response are as direct and sincere as a love letter from mom.

Possibly the S550's greatest strength lies in its understatement. From the outside there's a subtlety to the S550's presentation that precludes it from exclusivity as a rich-man's mantelpiece. It manages to be better than a Rolls or Bentley without brazenly broadcasting either its status or its competence.

An Over-the-Top Interior
Sure, daily driving an S550 is like employing a Cray Supercomputer for kindergarten arithmetic. But there's no denying the sedan's suitability at the task of comfortably and safely moving people: near or far, fast or slow.

Largely it's the S550's posh interior that's got this job nailed. Real leather, not Mercedes' knock-off, MB-Tex, is standard and can be upgraded to Napa or semi-aniline. And it's everywhere. Literally. The dash, the doors, the center console and, of course, the seats are covered with the stuff. There are more heated surfaces (including the center console and door armrests) than at Yellowstone Park in August. The Premium 1 Package ($4,500) adds heated, ventilated and massaging seats with active bolsters, which brace occupants against cornering forces.

Though the S550 might not project Rolls-Royce effrontery from the outside, it undeniably evolves from luxury into plain silliness inside. The Air Balance Package ($350) adds an "active perfuming system," which gives the otherwise elegant sedan a distinctly Glade-scented stink. Other scents are available and, of course, it can be disabled. There are subwoofers in the firewall. The high beams dim themselves. And the ambient lighting is adjustable over a range of seven colors — including pink and purple.

If gratuity has embodiment, this is it.

The Tech Continues Inside
The dash is unique even in the world of ultra-luxury. Two 12.3-inch display screens — one for instruments and another for navigation-audio and other functions — make up the visuals. Mercedes' COMAND interface is standard and is both intuitive and relatively uncomplicated given its many functions. Map zooming and traffic display are quicker than in any other competing system, and screen resolution is among the best we've witnessed.

Also, there's a Web browser built into the COMAND system, which uses an embedded modem to access the Internet. And, of course, the car is a WiFi hot spot. Subscription to the Mbrace apps service is required to use either.

It's the backseats where much of the true luxury resides. The Executive Rear Seat Package and Executive Rear Seat Package Plus offer the most horizontal reclining seat in the segment and folding tables, respectively. Our tester offered neither but did come with power-operated memory seats and the Rear Seat Package, which provides four-zone climate control and a power-operated footrest on the passenger side.

Also, big people fit. Our 6-foot, 4-inch vehicle testing assistant reports comfort in the backseat.

The Best Place for FroYo
Passing its most rigorous test with flying colors, the opulent sedan blasted through a freeway entrance ramp without raising our passenger's blood pressure — or her attention from her smartphone. So it was unsurprising when date night evolved from an elegant dinner to sucking down frozen yogurt inside the S550, Burmester audio at full crack. If that's not the true measure of success in a car like this, we don't know what is.

Starting at $93,825, the S550 is about $10,000 more costly than a similarly equipped Audi A8 or BMW 7 Series. Our tester, equipped with most of the marque's most notable tech features, totaled $116,340.

And if what you want is a large sedan offering equal parts understated luxury, top-shelf comfort and enough technology to (literally) drive itself, you'll be hard-pressed to find a more excellent candidate. Even our insurance actuaries agree.

The manufacturer provided Edmunds this vehicle for the purposes of evaluation.