While nimble and powerful, we wouldn't call the base SL 550 a sports car, but it's absolutely the luxurious, sporty touring roadster those SL loyalists have loved for so many years. It's essentially a Teutonic homage to the classic Thunderbird, albeit one with now-space-aged technology and comfort that older cars have never offered.
On the ride and handling front, we suggest you reread the first paragraph one more time. Then you'll understand better how a body that's stiffer and 275 pounds lighter, and how a boatload of add-on electronics, have changed and can change the driving character of the SL. Thanks to lots of aluminum, it's lighter to its core, a feeling amplified by electric power steering that's new to the luxury roadster. Engineers have set up the Direct Steer system with one programmed set of responses that depends on vehicle speed and distance off center, while transmission and suspension settings have at least two driver-selectable modes. Direct Steer lets the SL feel more stable on center, while it gets quicker responses farther off center to minimize wheel movement. But like other electric steering systems, it's given up some ground, some vital feedback, and some steering heft--some of the haptic stuff that's arguably a hallmark of Mercedes cars.
At the same time, the SL comes either with a conventional multi-link suspension with two-mode adjustable shocks or with the upgrade Active Body Control active suspension. It also has torque vectoring--inside-wheel anti-lock braking that tightens cornering. After a couple of hundred miles split among all versions (there's a sport package on base models), we grokked more to the base car's more natural feel. It's comfortably tuned without overstepping into loosely plush too often. Long, low rises can set up bounding motions in the suspension, and body roll's never far away, but the same holds true for a base Jaguar XK or Maserati GranTurismo. Good weight balance helps the SL turn in neutral feel in tight esses, and just a nudge of the throttle liberates all that torque, and pulls a wide line closer to true.
Adding on the ABC suspension doesn't add much to the SL driving experience, in our view. It does as promised--it flattens out the SL's ride, but that raises the sporting stakes. Great in sweeping turns and lightly undulating surfaces, the quick throttle, light and nonlinear steering, torque-adjusting brakes, and constantly adjusting shocks don't work as well during hotter performance runs. Turn in sharply on an ABC-equipped car, and the quickest transitions go soft-focus, just when the brakes want to hone the corner down further, just while the suspension is still filtering off the abrupt highs and lows it's finding in the corner.
The 4.7-liter twin-turbo V-8 in the SL 550 whips out 429 horsepower, up strongly from the prior car's normally aspirated base V-8. More astonishing is the torque, which escalates from 391 pound-feet to 516 lb-ft. Power's capped at a 6300-rpm redline, but most of it is available at 1600 rpm, giving the SL 550 extremely powerful acceleration. Mercedes pegs 0-60 mph times at 4.5 seconds, almost a second quicker than last year's edition, and top speed in this model is limited to 130 mph.
A seven-speed automatic with paddle controls does its part to keep the SL's rear wheels in good graces with the massive output, and with the EPA. With manual, eco, and sport-shift modes, the gearbox has less real range in its acting portfolio than you'd think, but it's consistently a good, quick performer. No official economy numbers have been logged, but Mercedes says gas mileage should improve by as much as 30 percent; the same drivetrain in an S550 sedan netted us 25.5 mpg on a five-hour, 85-mph interstate trip just last month.
With a special AMG-built 530-horsepower twin-turbo V-8 and wet-clutch seven-speed AMG automatic transmission, the SL 63 AMG is a serious step up in performance, and at about $40k more than the SL 550, it feels a lot more exotic from behind the wheel. The SL 63 AMG gets to 60 mph in a scorching 4.5 seconds, and with a $9,000 Performance Package you get up to 557 hp and 664 pound-feet, with a top speed bumped to 186 mph and 0-60 lowered to 3.9 seconds--accompanied by a glorious, pulsating bark of a soundtrack that far outdoes the M6's muted whir.
And if that's not enough, you can step up to the $209k SL 65 AMG and its twin-turbo V-12, making a mammoth 738 pound-feet of torque.