For Mercedes' top of the line sedan, S stands for "sizzle."

The sedan in question is the S63, arguably one of the most outrageously fast and luxurious sedans in the world.

Equipped with a 6.3-liter, 518-horsepower V-8 engine (rated at 11 mpg in the city and 17 on the highway) that hits 60 mph in 4.5 breathtaking seconds, the S63 is a marvel of technology and razzle-dazzle features.

All of this comes at a sizzling hot price. The base price is $127,000, and options on our test model, such as the Distronic PLUS cruise control system, the AMG performance package, heated and ventilated seats, and other items brought the final price to $146,665.

And you'll pay at the pump, too. Plus, because of its low gas mileage, buyers have to pay a $3,000 gas guzzler tax.

If you're prepared to pay the price, you'll get in return a motoring experience unlike anything else in its class -- or anywhere else, for that matter.

The leather seats have bolsters that inflate to hold you tight as you roar around corners. And if you've pressed the right buttons, you'll get a massage that you can customize for just about any part of your upper torso. If your fanny gets too warm, just chill the seats. Too cold? The seats warm up, too.

You'll also see that there's a multimedia slot that allows you to bring digital music into the car by plugging in your memory card.

There also is hands-free communication with voice activation. And the Harmon/Kardon audio system is out of this world.

But the real star of the show is the performance. You hear a deep-throated growl when you start the car, accentuated by a rumble not unlike that of a well-tuned muscle car.

Accelerate and the car leaps forward like a panther -- quite apropos given its sleek, muscled, catlike profile that has subtle, yet clearly muscular character bulges in all the right places.

This is one of the few Mercedes models in which there really is drama during acceleration; usually these cars are so serene about hitting high speeds that you don't even know what's happening.

Handling? Flawless. Driving this car through curves is reminiscent of bobsled races. The steering is perfectly balanced, and the console shifter connection -- if you choose not to use paddles -- is crisp.

By the way, accident avoidance is very much part of the picture here. The "Pre-Safe" system is constantly monitoring driving conditions so that if need be, it can prepare the car and you for an impending accident.

If that happens, electric tensioners tighten the seat belts of the front-seat occupants. The passenger seats are adjusted instantly by raising the headrests to put you in the best position for effective use of air bags. And if the car determines that a collision is about to happen, the windows and sunroof are closed automatically too.

And if in an emergency situation you are not applying enough pressure to the brake pedal, the car's "Brake Assist Plus" system takes over and does that for you.

All of this technology is but a prelude to what most cars will have in a few years. The S Class has a reputation of being ahead of the curve with technology.

Challenges? Just the sheer complexity of operating this car is one. If you have no patience for trying things out, adjusting and modulating, and if you don't have time to read the owners manual, don't buy this car. You won't get the most out of it.

As I've said so often with Mercedes products, the COMAND system that governs audio, navigational and other functions can be maddening. And my least favorite feature is the cruise control stalk, which you find yourself inadvertently engaging when groping for the turn signal.

Aesthetically, the radical transformation inside and out that all S-Class models have undergone may seem way too edgy and contemporary for the more conservative folks among us, but I loved it.

And there are few cars like the S63 AMG out there. If you can afford it -- and that's a big "if" -- go for it.