Greg N. Brown, Contributor
From its stylish museum in Stuttgart to the Classic Centers that caretake and restore vintage Benzes, Mercedes-Benz is particularly adroit at using the golden glow of past glories to illuminate the appeal of its current automobiles. It was in this nostalgic context that the company developed the 2007 Mercedes-Benz SLR McLaren 722 Edition.
The supercar honors the silver 300 SLR Stirling Moss drove to victory in the 1955 Mille Miglia, the 1,000-mile Italian endurance race from Brescia to Rome and back. Pasted on the side of Moss' winning SLR was "722," the car's starting time of 7:22 in the morning, and it is now one of the most recognizable numbers in racing history.
Somewhat surprisingly, the concept of a sportier McLaren SLR came from current SLR owners, who wanted their next McLaren to be less grand tourer and more purebred sports car. Mercedes-Benz responded with a stronger engine, stiffer underpinnings, bigger brakes and improved aerodynamics. Plus, the few cosmetic touches designed to separate the 722 Edition from its predecessor are in context and avoid the aesthetic questionability of so many "specials."
Sparking up the performance
In the world of the supercar, more is always better, so the electronics that control the hand-assembled AMG-built supercharged 5.5-liter V8 were revised, increasing output from 626 to 650 horsepower and torque from 575 pound-feet to 605 lb-ft.
Among the high-tech touches in the all-aluminum engine are an enclosed crankcase sump of cast aluminium, and twin oil injection to cool the forged pistons. The dry-sump oil system also draws on Mercedes' track experience and sites the engine low in the chassis for better weight balance. The belt-driven compressor's two screw-shaped aluminum rotors are Teflon-coated to decrease power-sapping friction, and a pair of air-to-water intercoolers minimizes the heat of the compressed air to maximize output and torque, which is delivered more quickly than in the current engine.
Push the start button on top of the shift lever and the side pipes surround you with an aggressive growl. Push the accelerator pedal, and the deep rumble is accented by a metallic supercharger shriek that rips aural tears in the atmosphere. We'd love this engine for its sound alone, never mind its free-revving grunt, which pulls the long nose toward the horizon with almost fearsome determination.
Mercedes says the rear-wheel-drive SLR 722 will sprint from zero to 62 mph in just 3.6 seconds, 3/10ths faster than the "standard" SLR. Top speed is a tad improved, too, though the jump from 207 to 209 mph is, for most mortals, a purely theoretical achievement.
Tightening down the chassis
Lowered about half an inch and suspended by stiffer springs and shocks, the retuned chassis gives more stability at high speeds, though this more aggressive personality comes with some compromise to ride quality. Body roll has been reduced, says Mercedes, by more than 20 percent, for more agility in the corners, but the reduced compliance also means more jolting over the bumps, especially from the rear wheels.
The lightweight aluminum construction of the double-wishbone suspension delivers quick response to the road and excellent wheel control, with the lower links arranged to supply negative camber, and thus better contact with the road, when the springs compress. As on a Formula 1 car, the front antiroll bar is positioned above the axle so the smooth underside of the car is not disrupted, vital to the car's improved grasp of the road.
New, lighter 19-inch forged aluminum wheels, colored palladium gray to match the trim around the lighting, reduce unsprung weight and allow larger 15.4-inch brake rotors up front. Sourced from Brembo, the new braking system uses carbon-fiber-reinforced ceramic discs for formidable deceleration, while a reformulated ESP control system helps keep the car pointed in the right direction when the surface gets slick — or when the driver gets too frisky with the throttle.
Turn off ESP, and judicious use of the accelerator will cause an abrupt leave from the line, but once under way the power delivery is crisp and the shifts timely, especially when the paddles are used in the five-speed automatic transmission's "Manual" mode. In "Comfort," the engine will balk slightly, especially when reversing or getting going, but the buyer of this car shouldn't be tooling around in that mode anyway unless it's to take the mother-in-law back to the rest home.
Slipping through the air
Some 100 hours of wind tunnel work reconciled the difficult task of increasing downforce while also reducing drag. The front carbon-fiber air splitter increases front downforce by 128 percent, says Mercedes, something that became apparent during several naughty high-speed runs through the desert of Dubai.
At the rear axle, discrete wheel spoilers reduce air swirl to help keep the tail planted as the car approaches takeoff speeds. The electronically deployed air brake, which rises at about 75 mph, produces a further gain in downforce at the rear axle for more stable handling at high speeds. It also deploys during heavy deceleration, partially compensating for braking's front-biased load distribution.
Engineers have also managed to reduce the 722's weight by 97 pounds. Gains come from a lighter oil tank, lighter wheels, aluminum shock bodies, removal of interior carpeting and redesigned interior panelling and insulating materials. It's not a lightweight at 4,268 pounds, but every little bit of reduction helped toward improving the dynamics.
Distinguishing elements include black-painted air outlets on the hood, and front and rear light clusters with palladium gray surrounds. The SLR 722 Edition is available only with a crystal antimony gray paint finish that evokes the look of the Moss racecar. All body panels are carbon fiber.
An attractive combination of semi-aniline leather and Alcantara covers the sports bucket seats and gives the interior a distinctive look and feel. "300 SL red" stitching throughout, the 722 insignia on the head restraints and red seatbelts add more visual impact, while widespread use of carbon fiber throughout the interior is a further visual connection to the highest forms of racing.
The seats, however, aren't comfortable. They punched us in the kidneys all day long. Custom padding is available, which would probably fix that problem. The A-pillar and mirrors can also block views of the apex during cornering, and it's impossible to get in and out of without the paparazzi revealing to the world whether you dress "regimental" or not. The low-slung front end will undoubtedly give the carbon-fiber repair shop plenty of overtime.
Driving the 722 Edition
The technological and aesthetic improvements are all well and good, but is the 722 Edition a better driving machine than the SLR that came before? In a word, yes. It's lighter and more aerodynamic, and the revised throttle curve and quicker torque delivery make it leap from the line as though it were setting out on a qualifying lap.
It's also more expensive. Pricing hasn't been finalized, but it's expected to cost somewhere between the current SLR's $452,000 and a half-million bucks when it goes on sale this summer.
Even if you've got the requisite wad, there's no guarantee an SLR 772 Edition will end up in your stable. McLaren's F1 works in Woking, England, will build only 150 examples, largely by hand, and how many 722s will come to America is unclear.
Regardless, Stirling Moss better be getting the first one.
Edmunds attended a manufacturer-sponsored event, to which selected members of the press were invited, to facilitate this report.
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