2008 Mercedes-Benz

Abstract: AutoWeek.com News: Mercedes-Benz has its sights set firmly on the Lamborghini Murcielago LP640 roadster with its rapid new SLR roadster. The open top, which goes on sale in North America this fall, is the second model to emerge from a joint venture between Mercedes-Benz and McLaren Cars

Expect the SLR roadster to top $500,000 and plan on it being extremely hard to get even at that price.

Based on the three-year old SLR coupe, the roadster will be assembled in limited numbers at McLaren’s Paragon factory in Woking, England. Production begins in September following the car’s public unveiling at the Frankfurt motor show.

In creating the SLR roadster, Mercedes has adhered closely to the formula used on the SLR coupe. Visual differences between the two are limited to the roof structure alone. In other areas, they are identical, right down to the dramatic scissor-action vertical doors and integral rear wing that automatically deploys at high speed to provide added downforce and acts as a stabilizer under extreme braking.

Despite favoring complex folding hardtop arrangements on the SLK and SL roadsters, Mercedes-Benz has chosen a traditional fabric top for the SLR roadster. The multi-layered structure electrically opens in less than 10 seconds once it has been unlatched from the windshield, Mercedes says. An aluminum section integrated into the top’s forward section acts as a tonneau cover to preserve the car’s dramatic exterior lines when the top is down.

Owing to the inherent stiffness of the SLR’s carbon-fiber monocoque, Mercedes says the transformation from coupe to roadster has been a relatively simple process, requiring only subtle modifications such as additional bracing within the A-pillars.

The SLR roadster is powered by the same supercharged 5.5-liter V8 engine as the SLR coupe on sale since 2003. Mounted up front underneath the new open top’s long hood, the three-valve-per-cylinder unit punches out 617 hp at 6500 rpm together with a sturdy 575-lb-ft of torque at 3250 rpm. Power is channeled via a five-speed automatic gearbox and a limited-slip differential to the rear wheels.

Despite the various modifications to accommodate the roof, Mercedes claims there has been no significant gain in curb weight with its new model. As a result, the SLR roadster manages to match the SLR coupe in the sprint to 62 mph with a time of just 3.8 seconds. Top speed of 207 mph is also identical. By way of comparison, the 6.5-liter 640-hp V12-powered Lamborghini Murcielago LP640 Roadster is said to hit 62 mph in 3.4 seconds and nudge 211 mph flat out.

Mercedes is making big claims about the SLR roadster’s safety credentials. Along with unique carbon fiber crash structures integrated into its front- and rear-ends, it also receives front, side and knee airbags as well as fixed roll hoops behind the seats and an armada of electronic driving aids, including the German car maker’s usual ESP, ABS and Brake Assist systems.