Under the Hood

The 2008 Mercedes-Benz C63 AMG is powered by a 6.2-liter V8 and is the first engine designed wholly by AMG.

AMG's First Engine

A brand-new 6.2-liter V8 motivates the C63. It's the first engine designed wholly by AMG and shares nothing with any regular Mercedes mill. For this application it's restrained to 441 horsepower and 443 pound-feet of torque, but easily makes over 500 horses in larger AMG models like the swank CL63 coupe and swoopy midsize CLS63 sedan. And even with this modestly tuned version, the C63 out muscles V8 rivals BMW M3 (4.0 liters, 414 horses, 295 pound-feet), Audi RS4 (4.2 liters, 420 horsepower, 317 pound-feet) and Lexus IS-F (5.0 liters, 416 horses, 371 pound-feet).

As expected of Mercedes, the "AMG 63" is a state-of-the-art engine. Naturally, it's a twincam design with four valves per cylinder, variable valve timing and a two-stage intake system, all electronically controlled to maximize both high-end power and low-speed grunt. In addition, this V8 is made almost entirely of high-tech, high-strength silicon-aluminum alloy, with cylinder bores treated by an exclusive process that makes them twice as hard as conventional cast-iron surfaces, or so Mercedes claims. The low-friction cylinder walls and low-mass valvetrain contribute to a giddy 7300-rpm redline, but you don't need to go that high, unless you want to. Though power peaks at 6800 rpm and max torque appears at 5000, this engine really pours it on from as low as 3000 revs.

Mercedes is proud to note this engine is hand-built at AMG's Affalterbach facilities by 50 technicians organized around a "one man, one engine" philosophy. That means assembly of each engine is the overall responsibility of a single person, who finishes the job by attaching a plate bearing his signature. Handcrafting engines is hardly new, but it's another thing expected of an outfit with AMG's reputation. And in case you're wondering, Mercedes says each engine takes 2.7 hours to build. Think about that.

Brainy Transmission

The C63 debuts a new seven-speed automatic transmission called AMG Speedshift Plus, the only one offered. It's basically the unit used in other AMG models and can be shifted manually via a console stick or a pair of steering-wheel paddles. The new wrinkle is a "double-declutching" feature that provides "rev-matched" downshifts in the driver-selectable Sport mode. In other words, the engine/transmission computer automatically "blips" the engine when, say, braking or slowing for a corner. Besides smoothing the shift itself, this feature, Mercedes says, helps minimize weight transfer from the "engine braking" effect that can upset cornering stability on lifting the throttle, especially at higher speeds.

There's also a Comfort setting that shifts at lower rpm for the sake of fuel economy--such as it is--plus a full manual mode. However, as with a growing number of performance-car automatics, this one can be shifted with the paddles in any mode. Doing so in Comfort or Sport overrides automatic drive; the transmission returns to shifting itself about 10 seconds after your last paddle prod.

Not Just a Shoehorn Job

Like its German peers, the 2008 Mercedes-Benz C63 AMG is more than a smallish car with a big engine shoehorned in. The V8 installation required several upgrades to the basic C-Class structure, which prompted other changes in the name of performance.

For starters, the V8 weighs 80 pounds more than the V6s in the C300 and C350 models, so it sits two inches closer to the firewall to keep the C63 from being unduly nose-heavy. That, in turn, required a stiffer front subframe and impact beams to maintain crash protection, and engineers took advantage of this to give the C63 a 1.4-inch wider track, a larger stabilizer bar, and stiffer wheel spindles and bearings--all very, very good for handling. Steering was recalibrated to suit.

The wider axle necessitated new front sheetmetal, which is why the C63 wears an exclusive power-dome hood and wider front-fender flares, plus a meaner-looking grille and lower fascia. Completing the new visuals are matching rear wheelarches, modestly flared lower-body rails, and a specific rear bumper cradling a quartet of exhaust pipes.

The C63 retains the basic C-Class suspension with all-around coil springs, an antiroll bar at each end, front struts on lower control arms, and a multi-link independent rear. AMG substitutes stiffer springs and shock absorbers, plus larger antilock disc brakes with diameters of 14.2 inches fore, 13.0 inches aft, all drilled and vented to dissipate heat--a performance-car must. Upsized rolling stock is also expected, and the C63 has it, with handsome five-spoke forged-aluminum wheels mounting 235/40ZR18 tires in front and 255/35ZR18s in back.

A final chassis change involves the Mercedes-AMG Electronic Stability Program (ESP). This antiskid/traction-control system now adds a full "Off" setting, plus a "Sport" mode. The latter delays ESP intervention to higher cornering speeds than normal "on." A prudent driver can thus indulge in a little two- or four-wheel sliding and still have some electronic backup. The added settings are meant to underscore the C63's handling credentials as a gauntlet-throw to the ever-agile BMW M3. The three-mode ESP is a C63 exclusive for now, but should shortly show up in other AMGs.

The 2008 Mercedes-Benz C63 AMG rides on 18-inch five-spoke forged-aluminum wheels.