Mercedes-Benz SL-Class Performance
The SL-Class 550 can sprint to high speeds in a short time and in relative comfort. "The SL is more luxury touring car than sports car, yet it was extremely capable of devouring the road effortlessly," writes the Kansas City Star.
Acceleration and Power
The SL550 is powered by a 5.5-liter V8 engine that makes 382 horsepower at 6,000 rpm and 391 pound-feet of torque at 2,800 to 4,800 rpm. It's rated by the Environmental Protection Agency to have a city/highway fuel efficiency of 14/21 miles per gallon. Cars.com says the engine "delivers waves of effortless power at any speed drivers are likely to encounter in the U.S.," and Edmunds reports that it's "enough to sprint from zero to 60 in just over 5 seconds." Though the Mercedes Benz SL-Class features more powerful performance-oriented trims, Kelley Blue Book concludes that the SL550 "is the best choice for mere mortals."
The seven-speed automatic transmission is a good match for the V8. "This engine, especially in concert with the seven-speed automatic transmission, feels as smooth as an electric turbine. Massage the throttle gently and shifts are almost imperceptible. Mash the throttle and each gear change is only a momentary hiccup in the engine's turbine-like thrust," writes the Kansas City Star. While driver-adaptive programming allows for the transmission to adjust to driver-style, Touch Shift lets drivers manually downshift and upshift by slightly pushing the shift lever left or right from the drive position. The Boston Globe says that, while cruising, the transmission "works its way up and down the seven gears like a piano savant tickling the keys. Push it hard, and it becomes a different transmission, holding gears through the ascending rpms of rapid acceleration, refusing to upshift from your lowest gear of choice as you exit a corner in hot fashion."
Handling and Braking
The rear-wheel drive SL550's handling dynamics are pleasing. "In general, the 2008 Mercedes-Benz SL-Class roadster offers a rewarding and refined experience behind the wheel," remarks Edmunds. "When pushing the SL hard, handling is impressive, thanks to the excellent grip and the Active Body Control that almost eliminates body roll." A test-driver for Cars.com reaches a similar conclusion: "I drove the SL550 on many different kinds of surfaces -- smooth and rough asphalt, concrete highways, muddy logging trails (just kidding, Mercedes) -- and found much to like about the roadster's ride quality." Best of all, the Boston Globe reports, "Significantly, there is virtually none of the cowl shake usually associated with a drop-top."
While most reviews have very little to say about the SL550's steering, Cars.com says, "Even though the SL550 has fairly light steering effort for a sports car, the speed-sensitive rack-and-pinion system's telepathic responses and road feel won me over."
The SL550's suspension system is composed of an independent four-link in the front and an independent five-arm multilink in the rear. Enhancing this system is Active Body Control (ABC) -- which adjusts each wheel's suspension in accordance with road conditions in order to best avoid vibration, pitch, dive, squat, and roll. Forbes writes that the system "maintains optimal handling and a smooth ride at all times, and enables the car to careen through even the sharpest corners at speed without a hint of body roll." Though Consumer Guide reports the ride to be "more jarring than expected on really rough pavement," the Boston Globe argues that it's well suited for both city and highway driving: "Do the slow urban crawl and it remains soft for gentle cornering or the absorption of city street imperfections," adding, "It's also like that in steady highway cruising."
Though the SL550's independent suspension impresses, its braking system doesn't. Still, Consumer Guide reports, "Simulated panic stops produced shorter than average distance." Standard on the SL550 are an Anti-lock Braking System (ABS), Brake Assist (BAS), and four-circuit electrohydraulic brakes -- which, based on driver input and driving conditions, transmit brake pressure to individual wheels as needed. According to Cars.com, "It takes a day or two to get used to the sometimes nonlinear pedal response of the electrohydraulically actuated brakes, which at times provide immediate stopping performance but can also startle the driver. There were occasions when I pressed the pedal and nothing happened until I pushed it farther down -- not a sensation you want when you're piloting a six-figure sports car through heavy traffic."