The great irony of the Mercedes-Benz SL is that, for decades, its name has stood for Sport Lightweight -- two characteristics attributable to not a single SL produced in the last fifty years. If Stuttgart would stop promising "sports car" levels of performance, we'd probably stop expecting Porsche 911 levels of involvement. If the engineers stopped calling the SL "light," we wouldn't criticize it for being nearly as heavy as an S-class sedan.
There's a new SL this year, and Mercedes is attempting a little revisionist history. Suddenly, we're told that SL stands for "Super Light" and always has, which of course it hasn't. On the bright side, finally there's an SL that delivers on its name. Although aluminum body panels have been used in multiple generations of SL, the new, R231-chassis car is built almost completely out of the material. In fact, less than a tenth of the car's structure, by weight, is old-fashioned steel -- and most of that is in the rollover structure inside the windshield's pillars, a location where you want as much strength as possible. The SL's construction method -- not just the material used -- is particularly impressive: The car has a genuine aluminum unibody, not merely a spaceframe with aluminum body panels attached. It's made of extruded, chill-cast, and sheet aluminum parts that are married with exotic bonding, rivet-ing, and welding techniques, and the entire firewall -- an intricate, single piece of aluminum -- is, according to Mercedes, the largest piece of cast alu- minum ever used in a mass-produced automobile.
Indeed, the SL's structure is so stiff that it feels as though you're riding inside a vehicle made from one enormous cast piece. Mercedes' nerdy numbers back up that subjective impression: the chassis is almost twice as rigid as that of the brand-new Porsche 911 convertible (see chart on page 98).
The new car is not only twenty percent stiffer than the last SL, it's also much, much lighter. At 3947 pounds, the SL550 weighs some 275 pounds less than your neighbor's year-old SL550 -- despite the more rigid structure and additional safety engineering that would have added 165 pounds to the old car. The R231 is also 2.0 inches longer than its predecessor, with a significant 2.2-inch increase in width. The retractable hard top's frame is now made of magnesium (for lightness) and can be lowered in less than twenty seconds, says Mercedes. Sadly, the SL still needs to be completely stopped to raise or lower the roof, making twenty seconds feel like forty. Worse, since the intricate choreography occurs in near-complete silence, you need to pay close attention to the display in the instrument panel that tells you when it's finished, or you'll sit there for another half minute wondering why it's taking so darned long.
The roof is the only thing about the SL that's slow. The SL550 we drove, badged as an SL500 in Europe, is an absolute rocket. Mercedes ditched the old normally aspirated 5.5-liter V-8 in favor of a direct-injected 4.7-liter with two turbos and an extra 47 hp and 125 lb-ft of torque. The V-8 now assaults those poor rear half shafts with 429 hp, flinging the car to 60 mph in a mere 4.5 seconds, 0.8 second faster than last year's car.
In typical Mercedes style, the V-8's considerable growl is more brutal noise than melodic music -- we'll wait for the forthcoming AMG models for that. (The 2013 SL63 AMG has a 530-hp twin-turbo V-8 and hits 60 mph in 4.2 seconds; the new SL65 AMG has a 621-hp twin-turbo V-12 good for a 3.9-second blast to 60 mph.) The SL550's real music will be heard coming from its standard Harman Kardon stereo system, which places 7.9-inch subwoofers in the front footwells, freeing up space in the door pockets where woofers would normally reside. Very low frequency sounds aren't directional -- your ears can't tell where they're coming from -- so the subwoofers' location is somewhat irrelevant. But the position allows for better deep bass response that, combined with the great imaging and clarity of the remaining speakers, morphs the SL into an amphitheater when you turn up the volume. Even with the top down at triple-digit speeds, you can forget about hearing the wind or tires or engine: you can't even hear yourself think.
Strangely, the optional $6400 Bang & Olufsen system isn't nearly as good. Mercedes says it still uses the Harman FrontBass system, but the bass response is not only weak, it's muddy and loose to boot. Of course, the signature B&O illuminated tweeters are works of art -- and they tweet out enough crisp treble to tickle the insides of your brain -- but the standard stereo is just plain better.
The new SL's interior is more opulent than that of any previous SL; every last piece is high-style, from the dash vents to the small, leather-lined, embossed shifter. The aging Comand system feels unnecessarily complicated compared with newer systems from other makers, and the gauges themselves look slightly plasticky and cheap, but overall, this is Benz's most glamorous and well-constructed interior. It's very roomy, too, feeling as spacious as a full-size luxury sedan that happens to be missing the back of its cabin. The seats are as comfortable as they are attractive, with shoulder supports that cascade down from the headrests like the collar of Cruella de Vil's puppy-fur overcoat. Powerful seat heaters and the optional Air-Scarf that blows gently heated air at your neck -- a luxury that seems absurd until you've experienced it -- extend the top-down season.
Truly absurd is the SL's g-meter display, which uses the monitor on the center console to display momentary and peak g-force readings. Equally as pointless is Comand's Facebook integration. The SL's average customer is approximately 132 years old, and neither of those features seems appropriate in this class of car -- perhaps Magic Bifocal Control would be more useful. Magic Vision Control is, in fact, standard, but it doesn't help there -- it's a new computer-guided wash/wipe system that sprays washing fluid directly in front of the leading edge of the windshield wipers to minimize the possibility of splashing cleaning solution into the interior. Magic Sky Control, which debuted on the new SLK, turns the SL's transparent panoramic roof opaque at the touch of a button. And, as you can imagine, the SL is chock-full of available high-tech driver aids (lane-keeping assist, automatic parking, blind-spot detection, adaptive cruise control).
The SL also has a standard mesh wind blocker that rises electrically from behind the rear seats. Had we risked our driver's licenses to examine roof-down cabin turbulence at the U.S.-specification SL550's 130-mph electronically limited top speed, we'd be able to tell you that your toupee would have no risk of flying away. We did no such thing. We did, however, probe the European-specification model's 155-mph limiter, and at that speed, there's less in-cabin turbulence than in most convertibles at legal interstate speeds.
The SL's brakes are unfazed by repeated use, even from very high speeds. Unlike the last SL's electric brakes, the new car's conventional hydraulic pedal feels natural, and coming to a smooth stop at red lights is no longer accompanied by the fear of accidentally tapping the car in front of you. Now, all the SL driver needs to be wary of is the active steering.
At only 2.2 turns lock-to-lock, it's seriously quick -- except that it's not. The SL uses a rack that's slow on-center but begins to quicken as you turn the wheel, like Porsche has used for years. But the transition, which begins after just five degrees of lock, is anything but linear, and with electric power steering that can never decide how much assist to provide, the steering not only relays little information about what's going on at the front wheels, it also gives no indication of how much the car will turn for any given input at the helm. It's among the least confidence-inspiring steering systems we've encountered.
But that doesn't stop the SL from being brutally fast on back roads. Optional Active Body Control keeps body motions to an absolute minimum, although it feels as if its adjustments are half a beat behind the car. The combination of a strangely nonlinear accelerator pedal, a hint of turbo lag, and a massive torrent of torque (516 lb-ft from 1800 to 3500 rpm) means the rear tires can be easily overwhelmed. Even when traction isn't an issue, the rear end loves to walk around under hard acceleration. That's something we've experienced in other Mercedes-Benzes, but it's more disconcerting here because of the unpredictable steering. Like its predecessors, the SL doesn't much care to be hustled. In fact, it falls apart at the limit, transitioning between understeer and oversteer with no advance notice -- a not-so-subtle encouragement for you to back off. A sports car it most certainly is not, but if you need to cover huge amounts of ground quickly, comfortably, safely, and in grand style, the SL remains a remarkably comfortable and capable, if not rewarding, grand tourer in a class of one -- right where it has always been.
The all-aluminum construction is game changing, dragging the SL out of the doldrums of the last SL's cost-cut DaimlerChrysler era and into the spotlight as the worthy flag bearer for an apparently reinvented Mercedes-Benz. Now, if Mercedes could just add the word "beautiful" back into the SL's design brief. The awkward steering aside, the SL's biggest flaw is the way it looks -- it lacks the visual punch of a $100,000 jewel, too closely resembles the cheaper SLK, and is saddled with disjointed front, rear, and sides that look like they were designed by three different people. That is because they were, in fact, designed by three different people. Maybe next time, the Germans will tell us that SL stands for Supremely Lovely -- and they'll make the roadster as beautiful on the outside as it is underneath its skin.