By Josh Jacquot, Senior Road Test Editor Date posted: 06-17-2007 If the 2007 Mercedes-Benz CLK63 AMG Black Series and 2007 BMW M6 could talk trash, things would get ugly in a hurry. The big-bore Benz would snort something about its 465 pound-feet of grunt, the kind of power that would leave the Bimmer's flame-surfaced sheet metal in a smoldering pile on the road. The high-strung M6 would make a remark about the Benz's boy-racer fender flares, silly bodywork vents and decidedly uncivilized exhaust note. You can imagine the slugfest that would follow, plenty of 500 horsepower bellowing through quad exhaust pipes and then R-compound rubber splattered across elegant grilles. Think of it: a total hammer-and-tongs cage match, testing these high-performance icons to their breaking point. And that's precisely how we approached this comparison of the 2007 Mercedes-Benz CLK63 AMG Black Series and the 2007 BMW M6. Price Wars Sorry to end the suspense, but it shouldn't come as a surprise that the Benz wins this contest given its $136,000 price tag — nearly a $27,000 premium over the M6. Or should it? The BMW M6 coupe and the M5 sedan have proven themselves worthy to us in the past. And this M6 came fully equipped, complete with $3,500 worth of Merino leather upholstery, BMW's $1,000 Comfort Access System, the $1,000 Head-Up Display and $1,095 HD and satellite radio. The price tag for this car comes to $109,190, as tested. For its part, the Benz has no options. But like the M6, it comes standard with a navigation system, automatic climate control and plenty of leather upholstery. So this AMG-built hot rod is not exactly a stripped-down track-only version of the CLK. Quite the opposite, in fact. There's plenty of opulence to go with its bad attitude. Still, these are serious performance cars and we weighted the scoring accordingly, with 30 percent of the final ranking determined by their merits at the track. The Important Bits There was a time when any comparison test that turned 1,000 horsepower loose on the public roads required a whole handful of vehicles. But in a world grossly mutated by public fascination with ever-increasing amounts of horsepower, only two are now required. And so here we have two grand coupes that attempt to make 500 hp a useful proposition on the street. The approaches, in each case, are quite different. Both coupes use large, front-mounted engines driving the rear wheels, but that's where the similarities end. The BMW's 5.0-liter V10 makes its power with lots of twist, as peak power arrives at 7,750 rpm and the redline lies all the way up at 8,250 rpm. Even the V10's peak torque of 383 lb-ft occurs at a lofty 6,100 rpm. Meanwhile, the Benz's 6.2-liter V8 takes the classic character of a V8 and pushes the envelope. Sure, this 32-valve DOHC engine belches out 465 lb-ft of torque, but it also does so at 5,000 rpm — a higher engine speed than is usually seen in an engine with this much displacement. This relatively high torque peak gives way to an even higher power peak of 6,800 rpm, when 500 hp is at your command. And without hesitation this V8 will bounce off its 7,200-rpm rev limiter while making a sound like God's own bulldozer. Put It Down These two cars also sport unusual transmissions, not the least because both incorporate seven gears. The M6 comes equipped only with a sequential manual gearbox, which is basically a manual transmission that relies on actuators and careful programming to do the work usually accomplished with a clutch pedal and the driver's left leg. Shift paddles on the steering wheel trigger each shift (or you can also toggle the gears in the traditional way with the shift lever mounted on the center console) and the automated process gives you quicker gearchanges, complete with matched revs during aggressive downshifts. There's also a completely automated mode so the transmission will perform like an automatic. Shift paddles are mounted on the steering wheel in the Benz, and the bizarre shape of the lever on the center console reminds you that it's meant only for changing shift modes. There's a mode in which the transmission will do the shifting on its own if left to its own devices, and there's a mode in which each gear will stay engaged until the driver selects another. The difference in these seven-speed transmissions lies in the fact that the BMW is fundamentally a manual transmission with an automated clutch, while Mercedes-Benz is basically an automatic transmission with a torque converter. The Benz's torque converter acts like a sponge between the engine and rear wheels, soaking up the roughness in the power delivery yet absorbing some of the power as well. And if you want effective rev-matching to accompany your downshifts, the Benz's torque converter can't deliver it, and it simply takes up the slack until engine speed catches up with wheel speed. Getting Involved Driving through the suburbs in the CLK63 AMG Black Series is only slightly more subtle than pacing a Formula 1 race with one — which is this car's full-time gig, by the way. Since it's intended to be a track car, the suspension setup of the Black Series can be tweaked in as many ways as Paris Hilton's legal record. Its ride height is adjustable and so are its damping rates and camber settings. Of course, all this must be done using tools and elbow grease. Meanwhile the BMW M6 doesn't offer any such track-ready adjustments, but at least the damping can be tuned from the comfort of the driver seat thanks to an electronic button mounted on the center console. Turns out this difference in the way the Black Series and M6 can be tuned for the road also proves to be a perfect metaphor for the way these cars drive. The Benz requires work. The responses of its chassis, steering and brakes are filled with useful information about what's going on at the interface between the tire and the road, as well as the physical forces acting on the car. But the efforts are high and the information packed into not-so-subtle jabs and twists. Steering inputs must be deliberate, yet the reward is proportional to the work — like dancing with a big lady who can really samba. The M6, by comparison, feels bigger because it is, some 2.6 inches longer in wheelbase and 8.6 inches longer overall. This additional length is a nuisance on a tight and twisting road and only slightly less burdensome in more open terrain. The M6's variable-ratio steering isn't as honest and its brakes lose their confidence-inspiring edge after only a few minutes of hard driving. We're talking about a very capable car here, one that manages to make use of 500 hp in a way that doesn't make you feel as if you're risking your life. But it just doesn't happen to be as inspired at the limit as the smaller, more intensely focused Benz. The Smackdown Line up these two brutes on the drag strip and the result is closer than you might think. This is partly because these cars weigh almost the same, as only 4 pounds separate the 3,914-pound BMW M6 from the 3,918-pound CLK63 AMG Black Series. When it comes to acceleration to 60 mph, the Benz gets the nod, achieving the feat in 4.4 seconds. The M6 gets there in 4.7 seconds. Only 0.2 second separates these cars when it comes time for acceleration through the quarter-mile, and the Benz covers this distance in 12.6 seconds at a trap speed of 116.7 mph, while the Bimmer does the job in 12.8 seconds in 115.2 mph. In any contest of outright cornering grip, the CLK brutalizes the Bimmer once again. The skid-pad smackdown proves pretty ugly, as the CLK sticks right up to 0.96g, while the M6 languishes at 0.85g. The driver's ability to balance the Benz with under- or oversteer is decisive in this contest, and the car communicates its intentions unlike any other Mercedes-Benz we've ever tested. By comparison, the M6's light-effort steering requires a more delicate sense of the cornering limit from the driver, and the car's nose-heavy weight distribution places far more of the burden on its front tires. Finding speed through the slalom cones was harder in the M6 where its larger size again worked against it, but the final results were very close, with the Mercedes achieving 67.8 mph and the BMW recording 66.2 mph. The Benz stops better, too. It produces an outstanding halt from 60 mph in just 108 feet. The M6 takes 114 feet to get the job done and on several occasions we drove it hard enough to encounter brake fade. Since it has to do the job with conventional rotors while the Black Series carries massive (and expensive) 14.2-inch carbon brakes, we weren't surprised. Be-muscled Styling If the conventional Mercedes-Benz CLK coupe is a butterfly, then this badass Black Series version has emerged from the AMG cocoon with a massive injection of growth hormone. Its huge fender flares are like veins bulging from beneath its overstuffed skin. There are carbon-fiber trim panels around the vents in front of the front wheels, while an oil cooler for the rear differential hides behind the aerodynamic apron under the rear bumper. And forged 19-inch wheels are wrapped in track-ready, R-compound Pirelli P Zero Corsa tires, 265/30YR19s in front and 285/30YR19s in the rear. There's simply no denying the purposefulness of the Black Series. The BMW M6, however, is a heavily styled car with a few high-performance details. There are hints of purpose, sure, but it doesn't claw your eyes out with its brutal intent like the CLK63. From most angles the combination of forms seems downright bizarre to us. If you can get your head around the M6's unusual sheet metal, you'll find hints of its ability hiding in the styling. Nineteen-inch wheels with 255/40ZR19 front and 285/35ZR19 rear Continental SportContact2 tires are the first clue. Inside, both cars are among the best in the business when it comes to materials, fit and finish. Leather is everywhere in both. We give the M6 a slight advantage here because its leather upholstery is rich, soft and abundant, while every control interface operates with benchmark precision. Even though we continue to struggle with much of the logic behind the layout and features of the M6, it represents an unrivaled bit of craftsmanship. Yet if it's driving that matters, then the AMG sport seats of the Black Series can't be matched for support. The three-way electronically adjusted bolsters in the seatback provide great support as long as you can squeeze into the seat in the first place. The Easy Choice Bottom line: The Benz wins this test, but not just because it's quicker and handles better. Nope. When you're talking about laying down this much cash, there's more to it than performance. For this kind of green we want something special. We want attitude to go with the speed, sound to go with the looks and exclusivity to justify the cost of entry. The CLK63 AMG does it all. And it does it in a way the haughty, if capable, M6 cannot, with fat fender flares, bad attitude and plenty of brawn to back up its trash talk.