Road Test: 2009 Mercedes-Benz SLR McLaren Roadster

I know why the caged lion roars. A Mercedes-Benz SLR McLaren Roadster on anything but a speed-unlimited road is caged, and certainly the SLR McLaren Roadster--or any Mercedes SLR McLaren--roars. And with all due respect to Maya Angelou and her singing caged bird, the roaring is more impressive.

We drove a 2009 Mercedes-Benz SLR McLaren Roadster up the Hudson River from New York City, The SLR McLaren was, of course, Mercedes-Benz's ultimate production car, a sports car designed with its Formula 1 partner McLaren Automotive, powered by a supercharged V-8 engine conceived and built by AMG, Mercedes' in-house performance division, and assembled by McLaren Automotive in its facilities in Woking, England.

The Mercedes-Benz SLR McLaren, offered first as a coupe with production beginning in 2004, was based on a carbon fiber chassis with a body, hood and doors of carbon fiber composites. High-strength bonding and riveting connected individual carbon components of the chassis and bodyshell. The aluminum engine mounts are bolted and bonded in place.

The SLR McLaren's chassis included a monocoque tub surrounding the passenger compartment to which cone-shaped crash structures were added to absorb energy in a collision, the first time, McLaren claims, carbon fiber was used for that.

The AMG-built engine displaced 5.5-liter and with a supercharger nestled between the banks of the V-8, producing in original form 617 horsepower. Just as impressive was Mercedes-Benz SLR McLaren's torque. At only 1500 rpm, the AMG engine produced 442 lb-ft of torque, maxing at 575 lb-ft from 3250 to 5000 rpm. The engine, equipped with side pipe exiting just behind the front wheel openings, had mufflers--such as they were--tucked in the rear of each front fender.

A fortified five-speed automatic transmission with steering wheel-mounted buttons for manual shifting were standard. Suspension was a racecar-like double wishbone setup front and rear, brakes fiber-reinforced ceramic discs, similar to those used in racing, with outstanding fade resistance and stopping power.
The body shape of the Mercedes-Benz SLR McLaren was developed for maximum downforce, with a flat bottom per Formula 1 cars, for smooth underbody airflow. That's the technical reason for the sidepipes, keeping them out of the windstream, although of course they do look cool.

Scroll down for more pictures of the 2009 Mercedes-Benz SLR McLaren Roadster.

Speaking of looking cool, the SLR McLaren's long hood and rearward seating position are due to engine placement. While the contours of the hood are intended to look and function somewhat like a Formula 1 car, any resemblance to a particular body part is merely coincidental. Sometimes a car's hood is just a car's hood.

It's the front mid-engine layout, with the engine well aft of the front axle line, that requires the cockpit to be so far back, even with the engine tucked under the cowl.

The SLR McLaren's engine isn't stuck back so far just for looks or any cool factor, but to balance mass front-to-rear. Traction for acceleration and braking is increased for both, as is agility and handling. Weight distribution is 51/49 front to rear. More downforce is added by a movable rear spoiler that raises automatically at sixty miles per hour, and then flips up to sixty-five degrees to provide extra downforce at the rear and more aerodynamic drag, functioning as an "airbrake."

Mercedes called the doors, which swing out and upwards, "swing-wing," allegedly to make access easier but they also attract attention.The gills in the front fenders aren't there just for looks either. They're open to the engine compartment for the release of hot air from under the hood.

The initial Mercedes-Benz SLR McLaren coupe was followed by the SLR McLaren Roadster, along with the higher performance Mercedes-Benz SLR McLaren 772 coupe and Roadster and the ultimate SLR McLaren, the Mercedes-Benz SLR McLaren Stirling Moss, named after one of the legendary drivers who piloted the original 1955 Mercedes-Benz SLR racers.

Our test car was a standard 2009 Mercedes-Benz SLR McLaren, and for our purposes it didn't matter whether it was a 772 or not (although we have sat in an SLR McLaren Stirling Moss and made vroom-vroom noises, which was really cool). With 617 horsepower on tap from its 5,439 cc supercharged displacement, an increase up to 650 would be academic, especially for our purposes.

The AMG-built engine starts with a push of a button under a flip-up cover atop the shift lever--it glows red when the key is inserted--and a bark and a rumble. It's easy enough to trundle about in Drive (with "comfort" and a quicker-shifting "sport" mode), allowing the automatic transmission to mind the ratios, but so much more appropriate to shift manually with the shift buttons on the SLR McLaren's contoured steering wheel (or a swipe at the shift lever).

Shifted manually, at least we have the basso rumble of the Mercedes-Benz SLR McLaren's on the overrun on downhills and the slight uphills and curves. Our driving area, however, is heavily infested with New York state troopers, so trundle we must.

Except a least for one entry to a four-lane divided highway. With slowing to a near stop and a quick look for an official presence in our rearview mirrors, transmission in first gear, we mash the loud pedal to the floor, really for just a smidge more than the 3.8 seconds Mercedes says it takes to get the Mercedes-Benz SLR McLaren Roadster to sixty-two miles per hour.
There's proof positive that earthquakes do happen in the state of New York. The earth moved for us. And momentarily, at least, the lion was out of the cage.

Illustration: 2009 Mercedes-Benz SLR McLaren Roadster. Photo byJohn Matras.

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