Last year, Mercedes-Benz's stunning CLS "coupe-sedan" stunned the high-roller set with its racy good looks. If you've been wondering what this sexy saloon would look like with just one pair of doors, get out your checkbook. Here it is, the 2007 Mercedes-Benz CL63 AMG.

We've already delivered driving impressions of the delicious CL550 and decadent V12-powered CL600, but the AMG-tuned CL63 is a different animal all together. It's the sharpest knife in the CL's drawer. The big Benz for the serious enthusiast.

V8 power: taken to the max
Naturally, the wizards at AMG, Mercedes' in-house hot rod shop, couldn't wait to get their hands on the S-Class-based CL. But rather than breathing more fire into the CL550's 5.5-liter V8, AMG developed the CL63's all-aluminum, smooth-as-silk 514-horsepower 6.3-liter V8 in-house.

The AMG-exclusive four-cam alloy V8 features variable camshaft adjustment, a highly rigid closed-deck crankcase, revolutionary new friction-fighting cylinder coating and oversized bucket tappets to suit its high-revving valve train. Its electronically controlled fuel injection system borrows from Mercedes-Benz practice, but incorporates new components to match this engine's performance potential. (Need we remind you that this is a normally aspirated power plant?) If need be, forced induction can (and perhaps will some day?) loft its output to well over 600 hp. Meanwhile, we're not complaining.

A stock CL550 packs 382 hp and 391 pound-feet of torque. The CL63's 6,208cc V8 makes 514 hp and a whopping 465 lb-ft of deep-seated torque, which makes it the world's most powerful, normally aspirated, series production V8. In other words, the CL63 really doesn't care which gear it's in; it'll boogie whenever you stomp on it.

The precise Speedshift 7G-Tronic automatic gearbox lets you match moods and roads with paddle-shifted Comfort, Manual and hyper-quick Sport (our favorite) settings. The Manual setting shifts 50-percent faster than the Comfort mode, 30-percent faster than the Sport mode, and lets you stay in your chosen gear at wide-open throttle and at kick down, so you get every bit of that horsepower, when you want it.

Fast company
Fire it up and a basso-profundo, un-Merc-like rumble from a quartet of oversize exhausts hints of wickedness under its sharply raked hood. Although the CL63 AMG gives away 36 hp to the Bentley Continental GT W12, Mercedes says it trounces the heftier Brit GT to 60 mph by 0.4 second and is just as quick in that sprint as the lighter BMW M6. The last M6 we tested hit 60 mph in just 4.6 seconds. Even better, Benz says the CL63 AMG is nearly as swift to 100 mph as Ferrari's 612 Scaglietti, for about half the sticker.

Like many German high-liners, this car's top speed is electronically limited to 155 mph, but you can opt for a Porsche-chasing performance package with a 186-mph limit.

No options needed
As befitting Stuttgart's range-topper, every conceivable handling and stability aid is standard, starting with improved Active Body Control (ABC), combined with AMG's supple-but-sweetly-firm sport suspension. The steering is precise, spot-on center and very consistent. Toss this big baby into a long sweeper, as we did on *****in' Bavarian back roads and you'll be amazed. There's no sturm, no drang, and virtually no body roll or frantic tire squeal from the huge 20-inch Yokohamas — just great grip and plenty of it.

A special AMG-developed high-performance braking system uses unique twin sliding calipers for the front brakes, single sliding calipers for the rears. The CL63 AMG's massive, fade-resistant brake rotors (15.6-inch front, 14.6-inch rear) are made of lightweight, race-inspired composite material, yielding outstanding sensitivity and surprisingly short stopping distances, time after time. ABS, brake assist and adaptive braking are all included.

We hustled the new CL63 AMG through tortuous mountain passes from Kitzbuhl, Austria, to Munich, Germany, reveling in this big coupe's ability to accelerate smartly, shrink distances, and entertain us royally with its split-second shifting and deeply satisfying exhaust note.

Looks are everything
AMG's stylists ensured you won't mistake their CL for the tamer Stuttgart version. There's a big fishmouth air intake under the grille, smart-looking titanium-painted headlamp lenses, distinctive aerodynamic side skirts, unique taillamps and rear fascia wrapped in an eye-pleasing wedge shape that's reminiscent of M-B's delicious CLS sedan-coupe. Inside, swathed in Passion leather, whether you choose walnut or aluminum trim, you're enveloped in luxury.

On sale next June for an estimated $125,000, the limited-production 2007 Mercedes-Benz CL63 AMG will raise the supercoupe bar, for just a few hundred enthusiasts. Better get in line.