Now, Mercedes has introduced an all-new S-Class.The exterior design, the interior design, and the onboard controls systems are entirely new, and all of the safety systems have been upgraded and even further integrated.Only a few parts and systems carry over from the previous-generation models, such as the air suspension system, the seven-speed automatic transmission, and most of the safety systems.

Competition among the best of the mainstream luxury cars is tough, but Mercedes may have risen to the top of the class with this ninth generation of S-Class models.

The S550 is powered by a completely new engine, the 5.5-liter V8 that has gone back to a 4-valve-per-cylinder design.The top-of-the-line S600 is powered by an upgraded version of the 6.0-liter 3-valve V12 twin-turbo engine currently used in the $350,000 Maybach sedans rated at 510 horsepower.

The S550 model offers extremely high levels of standard equipment, befitting its high market position.Virtually every comfort and convenience item is standard, with a huge option list to ease customization.The S600 adds Parktronic front and rear parking radar system, and the newly updated Distronic radar-controlled cruise control.The V8s come with the seven-speed automatic, while the V12 is equipped with a heavy-duty five-speed automatic.

Options include Active Body Control ($3900, standard on S600), Night View Assist ($1775), Parktronic park assist ($650), Distronic Plus cruise control ($2850), wood-and-leather steering wheel ($550), heated steering wheel ($450), dynamic multicontour front seats ($1800), Keyless Go ($950), power rear and side window shades ($700), Panorama glass roof ($1000), a reverse camera that displays on the COMAND screen ($1000), 19-inch wheels ($1200), 18-inch chromed wheels ($1000), and an electronic trunk closer ($500), Packages include the AMG Sport package of wheels, exhaust tips and body moldings ($5600), the P1A package of heated rear seats and Sirius satellite radio ($1250), and active ventilated rear heated power seat package ($2900).The S600 has a new designo Mystic White white-and-black interior and exterior design option for $9295, with only one other option, the 19-inch wheels for $1200.

The new S-Class safety package is unequalled in the class, with all the usual brake and airbag technology upgraded and Pre-Safe accident-readiness equipment made standard.The Brake Assist feature has been improved to Brake Assist Plus status, and is fully integrated with Parktronic and Distronic, respectively the radar-controlled parking and distance-controlling cruise control systems.The system now has two forward-facing radar systems, and can apply the brakes at any speed from zero up to about 125 mph and bring the car to a full stop without driver input.The company says the new system can reduce rear-end collisions in stop-and-go traffic by up to 75 percent.An added wrinkle to the revised PreSafe system that closes the sunroof, closes windows and repositions the seat in the event of an impending collision is that the air chambers in the backs of the multicountour bucket seats inflate to add support to the upper body in case of a rear-ender.The Electronic Stability Program, or ESP, which was introduced to the world on the S-Class two generations ago, is back as standard equipment, with two new features: trailer stabilization, and tire-pressure monitoring.

Another new offering is the optional Night View Assist.It uses infrared, not thermal imaging as the Cadillac's older systems.Using infrared headlamps, a tiny camera picks up and projects clear, sharp images of what's ahead of the car.The picture is displayed in the space normally occupied by the speedometer and tachometer, which change to bar graphs underneath the night vision display when it's activated.Unlike the thermal systems, the Mercedes system uses a sharper SIMOS display instead of a CCD, it does not depend on heat generated by engines or humans to create images, and can operate unaffected by temperature extremes.The system is a world first, and an exclusive S-Class option.

4Matic all-wheel drive is expected in the fourth quarter of 2006 for V8 models, but it is not available for the V12 version.A high-performance AMG model with a new 6.3-liter naturally aspirated V8 replacing the supercharged 5.

The exterior features a completely new, more aerodynamically efficient shape.Most noticeable are the exaggerated fender flares front and rear.New design cues include a more upright grille, new headlamps and new tail lamps, the latter with thick body-colored horizontal bars running through them, all tied together with lower body molding.For the first time in the design history of the S-Class, the decklid opening is not contained within the rear fenders, but instead extends out to the side of the body, with a distinctly raised position that looks a bit like the rear end of a 7 Series BMW.That was done for exactly the same aerodynamic reasons as on the BMW, to give the air rushing over the long, long roof panel a good place to separate cleanly from the body without causing drag.A side benefit is a huge trunk opening for easy loading.Active bi-xenon headlamps which illuminate around corners, and cornering fog lamps that illuminate the front corner areas of the car, are standard equipment.

This is the sportiest-looking S-Class ever with this new shape.Despite its increased size, width and height, it has the best aerodynamic rating in the entire luxury class, a 0.26 coefficient of drag, a figure that is among the best in the world, regardless of vehicle size or class.To keep weight down, the hood, decklid, door skins, and much of the door interiors are all made of various aluminum alloys, while the main body shell is made of high-strength steel.

A wide variety of wheel designs and sizes is available to suit each model, with a number of optional wheel and tire combinations.The S550 will come with nine-spoke 18-inch wheels with an optional five-spoke 18-inch alloy wheel or a chrome version of the same wheel or a 19-inch 22-spoke alloy wheel with 255/40R19 front and 275/40R19 rear tires or a 19-inch split spoke design with the same staggered tires.The S600 starts with a beautiful five-spoke 18-inch alloy wheel with 255/45R18 front and 275/55R18 rear tires.An AMG alloy wheel is available for the staggered 255/275 19-inch tire combination as well.

An optional AMG Sport package adds the big AMG wheels, a new front bumper with lower intakes and lamps, a new rear bumper, exaggerated side sills, and twin dual-outlet chrome exhaust tips.

The most striking change is in the COMAND system in the center of the dash that operates the radio, telephone, entertainment system, navigation system, and vehicle systems.Where the old system was sort of blue on gray, mounted low in the center stack of the console, the new system uses a large, deeply hooded and high-mounted 16:9 ratio full-color display screen, with a console-mounted knob that twists and pushes to change categories and change settings.Everything is done with the twist-and-push controller that operates like the BMW iDrive or Audi MMI systems, only better.It's far easier to use and understand, even without resorting to reading the manual, far more intuitive than the BMW and Audi systems or its predecessor.Select the vehicle systems and the display changes to a silhouette drawing of the car where you can customize 10 different settings to your preferences as easily as using a point-and-shoot camera.

Any item inside that was once black plastic with a white ideogram has been changed to a ridged matte silver button with a white-on-black ideogram above or below it that lights up when the lights go on to be visible in night driving.The driver's door panel is packed with controls for windows and mirrors, including a folding function, and in this case they fumbled.The switches that select the left or right mirror to be adjusted or folded are so tiny that the average driver will probably hit both at once until he or she is used to the change (they each light up with a red jewel to show you which side you're adjusting).The steering wheel has been redesigned to make the audio and other functions easier, with a pair of round controls in the spokes that can do up/down and left/right function selection and change, such as radio station, CD or MP3 track, volume, and muting.

Interior environment is controlled by a new switch panel at the center of the dash, with four vents and a new air conditioning system that is both vertically layered and capable of focused, medium, or diffuse air distribution throughout the car, with two zones in front and two in the ear, each with its own controls.Oh, and that thing that looks like a folded-up wood-grained, chrome-edged cellular telephone, on the console just behind the COMAND interface, is exactly that: a telephone dialer.

Another brand new wrinkle is a strip of ambient lighting in the cockpit that starts on the left door, goes all the way across the lower part of the dash, under the wood trim panel, and all the way back on the right door, creating a continuous ribbon of light that can be adjusted through five brightness levels by using the Vehicle portion of the COMAND system.A beautiful touch in a beautifully organized, visually exciting interior.

The new transmission shifter operates like the one in the new M-Class and R-Class SUVs: A tiny stalk on the right side of the column features up, down and in positions for Reverse, Neutral, Drive and Park modes, and all models come with three-mode shifting including Manual, Sport and Comfort shifting using the steering wheel paddles on the reverse side of the spokes, left for downshifts, right for upshifts.While we liked the new metallic interior panels very much, we didn't like the chrome tip on the shifter handle, because it's bright chrome, and it glares like crazy on a sunny day, directly where the driver is looking.We'd prefer the matte metal finish.

The CD/DVD system loads behind a panel under the HVAC system, and contains a slot for loading a PCM/CIA memory card to an internal hard-drive that will play up to 1550 songs through the Harmon/Kardon 5.1 Logic 7 600-watt, 14-speaker surround sound system.The system is comp.

Both transmissions upshift and downshift with the speed of a lightning bolt, with no hesitation whatever, regardless of shift mode.The transmission is designed to upshift at redline to protect the engine.

The Airmatic air suspension system has been retuned to give a far sportier and yet flatter ride than the previous S-Class could offer.The Adaptive Damping System shock absorbers and the steering effort and feel have also been retuned toward the sporty end of the spectrum with no dartiness, just a nice, progressive feel.The Automatic Body Control active suspension option cuts body roll at a rate 60-percent higher than the first version, and you can really feel it working when you throw the car into a fast, sweeping downhill curve like those we experienced on our Swiss-Italian test drive.

The new Brake Assist Plus brakes are, in a word, spectacular in their stopping power and stopping distance performance.With the new system, the brake lights go to full brightness and pulsate in the event of a panic or ABS stop.

We solved all of the mysteries of a brand-new car with a completely new switch layout and control system without looking in the owner's manual.It's that easy to go from one of last year's models to the 2007 S-Class, and we think that counts for a lot for the older portion of Mercedes-Benz's clientele with this car.It may be inordinately quick and fast on its feet for a big luxury car, but it's also easy to use and easy to learn.

It's also quiet.Mercedes-Benz says they spent an inordinate amount of time and money using human volunteers on the quiet aspects of the car, and called in some of the experts from the Maybach ultra-luxury car team.There are 170 individual pieces of sound and noise control equipment in the new car, including a patented front floor panel that cuts both noise and vibration.At continuous cruising speeds up to 125 mph, the S-Class is very, very quiet.

New Car Test Drive correspondent Jim McCraw filed this report from the Swiss Alps.