Luxury comes with nuances.

Little things denote one fine ride: The look of the thread on the dashboard stitching, the smell of the leather, the crystal-like headlamps. Even the sound of the trunk sealing itself closed after you push a button and walk to the driver's door it all projects luxury.

Knowing and understanding that some things in life are, well, just better is the gift of luxury. And some cars are better than others.

The Mercedes-Benz S-Class thrives in this knowledge. For generations, well-heeled boys have enjoyed this low spark of understanding and the hidden treasures of a well-made machine. The S-Class is pretty nice. It is the same as it ever was.

The S-Class has been one of the most revolutionary vehicles ever to hit the autobahn it defines the future with radical firsts that become commonplace for the unwashed nameplates.

The 2011 Mercedes-Benz S400 hybrid, however, is not as likely to follow a similar path. This is the S-Class sedan that is following, not leading.

Of course, at $91,000, it's the least expensive S-Class. It's also the most fuel-efficient, reaching 19 mpg city and 25 mpg highway with the first lithium-ion battery pack for the mild hybrid system. (By comparison, the $158,925 S600 gets 12 mpg city and 19 mpg highway.)

This is one of the inherent problems with a mild hybrid system on a big vehicle. While the improvements are considerable percentage-wise (30 percent better for the S400), the overall number doesn't sound very impressive.

Really, it is the 25 mpg highway is a big jump from the other S-Class models. But hybrid fullsize pickups offer similar mileage improvements with little public acceptance. If the word "hybrid" is slapped onto the trunk and front fenders, people expect the vehicle to produce big mileage numbers. Reality and physics rarely meet consumers' expectations.

The system is "mild" because it is not like other hybrids that can power the car at higher speeds on electric power only. The electric motor assists the gas engine, giving it a big boost.

The system also incorporates a start-stop system that cuts off the engine but seamlessly keeps running everything else. The hybrid system, which also includes regenerative braking to push electricity back into the battery, works with the German precision you'd expect.

Quiet intelligence

And don't underestimate the S400's Mercedes pedigree. It is pure Mercedes from bumper to bumper.

It still has that weighty luxury feel to its ride and handling. On the road, its gas-electric powertrain offers nearly 300 horsepower and 300 pound-feet of torque between its 3.5-liter V-6 and electric motor. That's more than enough power to get the 4,474-pound sedan moving. According to Mercedes, the S400 goes from 0 to 60 mph in 7.2 seconds and has a top speed of 130 mph.

Again, good but certainly not eye-popping.

The independent suspension and speed-sensitive, power-assisted, rack-and-pinion steering is well weighted. The S400 glides more than it rides. Its 124-inch wheelbase sucks up nearly every bump on the road in near silence. Also, the smaller engine (it's the only S-Class sedan with a V-6) and electric motor make the S400 nearly silent on the road.

And the S400 still comes with the many of the S-Class' safety features, one area in which Mercedes continues to lead the world. This car can detect if you're falling asleep, monitor your lane awareness correcting the driver if you start to slip out of your lane and keep the car straight in heavy crosswinds.

This car includes a radar system that will let you use cruise control in the Mercedes, it's called Distronic Plus cruise control even in thick traffic. It can actually bring the S400 to a full stop and then start up the car and move along before stopping again. There's no reason a Mercedes driver should be bothered with touching the accelerator or brake in stop-and-go traffic.

The radar system also creates a blind spot detection system that prevents you from moving into a lane with a car trailing in your blind spot. The radar is also part of Mercedes' Pre-Safe system that will detect when the car is about to be in an accident.

In the few seconds before a collision, the car will apply full brakes, tighten the seat belts, adjust the seats in the car for a safer position, and close the windows and sunroof if the car thinks there's potential for a rollover. All of these adjustments can help save the lives of a driver and passengers.

Simple control

And inside the S400, few will be disappointed.

The comfortable plush leather seats and simple, luxurious instrument panel are impeccable.

There's a certain understated appeal that the S400 offers. Luxury, in the case of the S-Class, is never in your face.

But it's found in the high-resolution, 61/2-inch screen at the top of the center stack controlled by the single knob on the center console. The metal wheel is easy to use by either spinning it or moving it forward and aft to move on the screen.

It's known as the Mercedes Command system, and it takes only a few minutes to get used to.

More importantly, the S400's interior is extremely roomy and comfortable in the front and back.

The S400 also takes on more aggressive looks with the redesign of the S-Class for the 2010 model year.

The well-proportioned body stretches out to create a low and long profile. The front end was toughened up, and the S400 includes special 18-inch wheels.

It's the nuances of the S400 that make this car look so nice.

A truly luxurious vehicle is like obscenity you might not always know how to define it, but you know it when you see it.