Power (and money) have a lot to do with choosing among the Mercedes S-Class models. The S550 comes with a 5.5-liter V8 engine that comes alive to the tune of 382 horsepower at 6000 rpm, with torque rated at 391 lb.-ft. at 2800 rpm. The 5.5-liter biturbo V12 that powers the S600 is rated at 510 horsepower at 5100 rpm and 612 lb.-ft of torque at 1800 rpm. All that power shows up in a staggering 0-60 time of 4.5 seconds for the S600. And, remember, this is a huge, heavy, fully-equipped luxury car.

The AMG lineup starts with the S63 AMG with a 6.2-liter V8 that makes 518 horsepower at 6800 rpm and 465 lb.-ft. of torque at 5200 rpm. The S65 AMG features a 6.0-liter version of the S600's V12 and significantly more power, to the tune of 604 horsepower at 4800 rpm and 738 lb.-ft. of torque at 2000 rpm.

Both five and-seven-speed 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 is tuned 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 are also tuned 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 significantly, 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 Brake Assist Plus brakes are, in a word, spectacular in their stopping power and stopping distance performance. With this system, the brake lights go to full brightness and pulsate in the event of a panic stop.

It's also quiet. Mercedes-Benz officials say 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, 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.

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