Behind the Line: Mercedes-Benz S-Class What gives this top-of-the-line Mercedes its appeal, besides its high price tag?

The German word b�rgermeister means "mayor." The literal translation is "master of the citizens." Not only in Germany but throughout the world, this is the type of buyer you'll see in the top-of-the-line Mercedes-Benz sedan.

In automotive terms, the S-Class is the ultimate indicator of affluence and power. The lowest-end version costs just a shade under $100,000 including tax, while the top model, the fire-breathing twin-turbo AMG, goes for more than double that amount. Chief executives and heads of state drive-or in many cases are driven-in S-Class cars. On both large and small screens, the big Benz sedan is used to signal that a character accepts only the best. Think powerful editor Miranda Priestly in The Devil Wears Prada or avaricious agent Arliss Michaels in the HBO series Arli$$.

It's not as flashy as a Ferrari. It's slightly less snooty than a Bentley. It's not trying to be a combination sedan and racer like the Audi A8, nor does it put you in touch with your inner accountant like the plush but conservative Jaguar XJ. And it's definitely not for everyone.

Not surprisingly, most S-Class buyers are men, says Valentine O'Connor, a spokeswoman for Mercedes-Benz. "Their average age is 55, with a household income of about $300,000," she says. Mercedes gets its statistics from Strategic Vision, a 30-year-old San Diego company that tracks the buying and personal habits of consumers.

So how does Mercedes keep its design edge and retain its loyal following year after year? For one, the carmaker has five research and development facilities in Stuttgart, Germany, where it explores all elements of design and ergonomics, says Michael J. Silverstein, a Chicago-based senior vice president with the Boston Consulting Group and author of Treasure Hunt: Inside the Mind of the New Consumer. "They are spending $2 billion per major model on research, design, and scale-up," he says. "They've invented 10,000 tests that they perform on their gizmo electronics. They are exploring all details from purchase through driveaway through usage of the latest gadgets. They are quite insatiable in wanting to know more about the consumer."

The S-Class first appeared in 1951, as the long-snouted, high-grilled 220. That model, one of the company's first new designs following the devastation of World War II, signaled that Benz meant to resume its pre-war position as the leading provider of rock-solid, prestigious sedans. Throughout the ensuing half-century, the company released a steady stream of innovations in luxury, design, technology, and safety. Today, both front- and backseat passengers can have their own moonroofs, and the rear headrests retract for a better view through the back window. The 14-position driver and passenger seats are leather armchair-comfy, and mechanical supports on either side of the driver's torso shift during turns to maintain equilibrium (and give a mini back massage) on curvy roads. The S-class was also the first car to include a crumple zone (1959), computer-controlled antilock brakes (1978), a supplemental restraint system including a driver's-side airbag (1982), and vehicle stability control (1996).

This year's edition offers an advanced version of Pre-Safe, a system that prepares the vehicle if an accident is looming. If the driver oversteers or the tires lose their grip, Pre-Safe raises the windows, closes the sunroof, shifts the seats upright, and tightens the seatbelts. Most noticeable to drivers, though, is Distronic Plus cruise control, which adjusts the vehicle's speed-all the way from a full stop back up to freeway velocity-in order to maintain a consistent distance from the car in front of it.

All that safety work without any luxurious play could make the Benz a dull car, which today's S-Class is not. The sturdy but slightly boring sedan of 20 years ago has evolved into a more handsome presence. Wheel arches curve out from the fenders, a vast hood covers engine sizes ranging from large to enormous, and doors still close like bank vaults. Even at top speeds, the interior is as silent as a meditation hut.

There are, of course, a few features that might be considered . suboptimal. Between the front seats, awkwardly placed buttons flank a control wheel that manages the telephone and the navigation and sound systems. Window controls are so subtly marked that they're hard to find, especially at night. The gearshift is a dinky wheel-mounted stub offering simply drive, reverse, or neutral (there are addition gearshift buttons hidden behind the wheel). But these are hardly deal-breakers.

Benz knows that top-of-the-line tastes vary. The company has been catering to successive generations of buyers for almost a century. Today's S-Class comes in four different models-all featured in our slide show-with variations in speed, strength, style, and trim. Laymen may not appreciate the subtler differences, but the people who can, well, they're the ones who matter.