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TARGET PRACTICE
With the addition of 414-hp V8, the BMW M3 is an even faster moving quarry than before, but Mercedes takes aim with the 451-hp 6.2 liter V8-engined C63 AMG. Has it hit the mark?
by DAN CARNEY.
photography by IAN KUAH
It would be entirely understandable if the BMW M3 suffered from raging paranoia, believing there is a target on its back. In truth, everyone is out to get the M3, and the shots from competitors, once laughably feeble, are becoming deadly accurate. When Mercedes’ AMG division says it is gunning for the Bavarian champion, we believe it. And when its challenger is packing a 6.2-liter, 451-horsepower V8, the case gets very serious indeed.
Remember how we could dismiss Mercedes’ sporting efforts previously? The cars were fast, sure, but not particularly nimble, and the clumsy automatic transmissions and intrusive electronic-stability-control systems tended to defeat any attempt at enthusiastic driving. The cars felt as out of place on the racetrack as Paris Hilton at a pie-eating contest.
The C63 proves this is no longer the case. At 3,814 pounds, the Mercedes remains 175 pounds heavier than the M3, and yes, it still only comes with an automatic transmission. But the C63 has 37 more horsepower than the M3 and enough surplus torque (a whopping 148 lb-ft) to mask its weight disadvantage, as well as smarter programming than before for both the transmission and the stability-control system. In addition, its front suspension has been thoroughly upgraded.
“The C63 is not a successor to the C55,” said Mario Spitzner, director of sales and marketing for AMG. “We said, ‘This time it is going to be different.’” As a result, the C63 is much more of a no-compromise product than its predecessor. The changes mean that the C63 is no pretender to the M3’s throne; it is a legitimate challenger.
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Power Play
For drivers who value long-distance, high-speed cruising comfort and the ability to burble effortlessly through commuter traffic in their sport sedan, the C63 delivers. Where the M3’s engine shrieks like a race car’s, whirling out power at high revs, and its 6-speed manual transmission indulges track fantasies, the C63’s larger-displacement powerplant and automatic transmission make it a much cooler customer. Yet the V8’s 443 lb-ft of torque accelerate the C63 with the relentlessly urgent pace of “The Bourne Ultimatum,” accompanied by the unhurried drumbeat of a throbbing, low-frequency exhaust note.
Impressive as the C63’s propulsive force is, the car is actually sandbagging. The same engine is rated at 507 horsepower and 452 lb-ft in other Mercedes applications. This handicap is achieved through the engine-management computer’s programming. Cutting back on the fuel injection and ignition timing schedules wasn’t enough to suppress the big block’s power, so the company had to resort to limiting the throttle, too. The intake and exhaust tracts differ from one car to another and new SAE requirements demand that manufacturers account for that, so an unfettered C63 might have slightly different numbers.
But the C63 is fettered, held back by the despicable demons of marketing. “The 451 horsepower was a positioning decision,” conceded Spitzner. “We decided that for this class, that was enough.” Sometimes “positioning” means a product’s position in comparison to competitors. But because it has more power than the M3, one suspects the C63 is handicapped to avoid embarrassing more expensive Mercedes-AMG models.
Surely, the engine-management software from one of the unrestricted models can be installed—unofficially—by a cooperative dealer, but if not, tuner shops will step in. That said, the C63 absolutely does not need additional power. The car’s output is “ample,” says Spitzner, and he is right.
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Transmission Transitions
The C63 enjoys not only the additional ratios of the AMG Speedshift Plus 7G-Tronic 7-speed transmission—the C55 had the old 5-speed box—but also its more advanced programming. As is expected in this class, the car carries aluminum shift paddles on its steering wheel for “manual” shifting. But people buy automatic transmissions for, well, automatic shifting, and in that guise the new 7-speed slushbox shines.
There are three different shift modes available: Sport, Manual and Comfort. The Sport mode bangs off shifts 30 percent faster than in Comfort mode, and when changing gears in Manual mode, the shifts are 50 percent faster. In a bid to cultivate the involvement of a manual transmission, the C63’s gearbox is programmed to blip a small over-rev on downshifts, simulating the sound of heel-and-toe downshifting. We found the effect to be too subtle to be readily noticeable. Powertrain experts on hand at the German press launch said that the system was still being refined.
Left to shift on its own in Sport mode, the C63’s transmission did an impressive job guessing the intended ratio, holding a low gear on short straights when another corner approached and downshifting on corner entry rather than under acceleration from the apex. It missed a couple of times, but overall it’s a much more capable automatic transmission than most.
None of this will convince true believers that an automatic can be a substitute for a manual transmission, but for the majority of drivers for whom shifting is usually a thankless, traffic-clogged chore, such a smart automatic is a good solution.
The electronic throttle—when it’s not busy restricting peak power—is calibrated very well. A seemingly obvious, but too-often-overlooked, detail on many new cars is throttle sensitivity. We like one that tips in from idle smoothly and predictably, and this one does; progress from a standstill is easy to control. As with the transmission, this is another example of the C63 doing what the driver wants and expects.
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Superior Suspension
When AMG decided that the C63 would be a no-excuses competitor, it determined that the front suspension of the C-Class was not up to the task. As with its 6.2-liter V8, Mercedes’ performance subsidiary decided to build its own. The new suspension maintains the same basic three-link MacPherson strut layout, but uses stronger components (rather than cast iron, steel is used; it’s twice as stiff) with revised geometry (courtesy of taller steering knuckles).
Most significantly, the front track is 1.8 inches wider for greater stability. Front springs are 10 percent stiffer, the anti-roll is fatter and the dampers are firmer. Stiffer bushings are used throughout, and a stouter coupling disk in the steering column contributes to faster response. The steering rack’s ratio is a quick 13.5:1 and the power assist is speed-sensitive. The result of all these tweaks is steering that is responsive when you turn the wheel yet retains the characteristic German autobahn “sneeze-proof” dead spot on center.
While railing through the curvy highways of the Taunus mountains west of Frankfurt, the C63’s handling proved to be a revelation, much sharper than the C55’s. At corner entry, the front plants itself and turns in confidently. Cornering grip is outstanding, and the tires voice no audible complaints under load. The car is responsive to mid-corner course correction and the steering provides reliable feedback, though effort is on the high side. This is appropriate, as the entire car conveys that solid, bank-vault feel for which Mercedes cars are renowned.
The larger 18-inch standard wheels (19-inchers are optional) provide clearance for larger brake discs, now 14.2 inches in front (up from 13.6 on the C55) and 13.0 inches in the rear (up from 11.8). The rotors are thicker than before, and are clamped at the front by six-piston calipers, with four-piston units at the rear.
The brakes provide good feel and feedback on the street, working unobtrusively while providing drag-chute-like stopping power. There is none of the squeaking or grabbiness experienced with some high-performance braking systems, and Mercedes’ hard-to-modulate electrohydraulic system is thankfully nowhere to be seen.
The C63 also advances ride quality compared to the C55. Perhaps it is just the car’s mass steamrolling bumps flat, but the C63’s ride is comfortable, even when the suspension is switched to Sport mode. In Comfort mode, the ride is as luxurious as one might expect, but absent the bomb-cratered roads of some northern U.S. states, there was little need for using the soft setting.
The C63’s electronic stability control is designed to work as a partner in crime rather than as a traffic cop, abetting fun instead of preventing it. The system has three modes: On, Sport and Off. The On mode is far less intrusive than the C55’s. The intervention was infrequent, but still more severe than we’ve experienced with the new M3 and 911 Turbo when invoked. In Sport mode the system allows larger drift angles before applying brakes to one or more wheels or cutting engine power.
But Sport mode doesn’t mean higher risk, because as soon as the driver brakes, the system reverts to the parameters of the normal program. Once off the brakes, it’s back to the regularly scheduled programming. The same goes for the Off setting; it prevents intervention, but the safety net is still ready to act if the driver jumps on the brakes. Fortunately, a smoky doughnut or fast ’n’ furious drift has never been executed while the driver was nailing the brake pedal.
There was no opportunity for track testing the C63, and the idea of doing burnouts in picturesque German villages seemed imprudent, so the outer limits of the stability-control system’s tolerance for mayhem went untested this time around. The locking differential might well have prevented any such hooliganism anyway, because the C63 puts the power down very effectively and with no drama—which is a shame, as some drama is fun.
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Judge by the Cover
Just as Mercedes raised the C63’s game dynamically, it has also moved ahead stylistically, evoking the company’s DTM racers—especially those gill slots on the sides of the front air dam. The new hood is stamped with a pair of power domes (if BMW’s got one, we’ll have two!) and a faux diffuser and small spoiler at the rear are the other significant points of differentiation from the lesser C-Class models.
Inside, the C63 is also dressed up with the usual details. A unique instrument cluster features AMG-styled dials and a speedometer that reads to 320 km/h on the German model tested. Computer geeks can get their share of digital information without even having to plug a laptop into a Pi data acquisition system: The car’s information screen offers Warm Up, Set Up, and Race modes, in which it displays the temperatures of the car’s vital fluids, the transmission and stability control modes, or a track lap timer.
As with all Mercedes models, the C63’s navigation system is plagued by the company’s inscrutable Command controller. While the BMW iDrive-esque setup is a change from the impenetrable button system used previously, it is no better. It is possible to learn the system well enough to live with it, but not to like it.
Despite the goal of torpedoing the M3, the C63 is instead a superb analog to that car. If the M3 aims at shift-it-yourselfers who want to hear the revs climb—think Honda S2000 with a back seat—the C63 pursues the much larger population of enthusiasts who enjoy taut, responsive handling, muscular styling and burbling V8 rumble in a low-effort package that makes the daily grind tolerable. So if the C63 doesn’t bulls-eye the M3, it is only because AMG was really aiming at a larger target.
From: SCI Magazine
