Gull-wing doors

The SLS AMG gets its share of attention moving down the road, but when the doors are open, practically everyone looks. (Ian Merritt/ photo)

More than just a return to a gull-wing design, the 2011 SLS AMG is the best-performing Mercedes ever made, despite some quirks that should be ironed out over time.

The SLS AMG was inspired by the 1950s Mercedes-Benz 300 SL gull-wing coupe and designed to go toe-to-toe with the best exotic sports cars in the world. With a price less than half that of Mercedes' previous supercar, the SLR McLaren, this one's actually priced to sell.

Exterior & Styling

The SLS AMG is a looker, though most observers agree the rear view is its least impressive. We brought the test car to a local collector who owns a 1955 300 SL gull-wing, expecting the classic to make the new one look bad, but the 2011 held up quite well. Its headlights and taillights are way different, and there's no chrome, but the proportions are similar, from the long hood and short front overhang to the upright windshield, which contributes to the SLS' relatively high, 0.36 coefficient of drag and EPA gas mileage rating of 14/20 mpg city/highway. Mercedes cars typically have a Cd below 0.3. That mileage rating also incurs a $1,700 gas-guzzler tax.

The SLS is also substantially larger than the old SL, with a greenhouse that's wider relative to the fenders. It's a less-distinctive look that you quickly appreciate regardless if you wedge yourself into the classic gull-wing. Seeing the two nose-to-nose showed one omission on the SLS: the rear quarter windows, which complete the original's look. Check out photographer Ian Merritt's gallery.

The car gets plenty of attention to begin with, but throw a door open and every man, woman, child and a fair percentage of nearby animals will turn their heads. Every dog that has ever chased a bird or a car will tremble uncontrollably. There have been several models with this door type, but a surprising percentage of admirers recall the 300 SL as the first. With the SLS, Mercedes is copying no one. Respect the wings.

Best-Performing Mercedes Ever

To put my praise in perspective, I'll need to lay a groundwork of criticism. When it comes to driving enjoyment, Mercedes isn't my first choice. Or even my fifth. The right formula has always been there: rear-wheel drive, decent weight distribution, ample power and any number of advanced technologies, some of which Mercedes itself invented. All the same, the company's cars haven't delivered as much performance or inspired as much confidence as BMW or, more recently, Audi, Infiniti and Cadillac (the CTS, specifically). Benzes hold their own, but they don't have the feel or the poise at the limits, and their incorporation of electronic aids hasn't been as deft.

So simply saying the latest and most expensive model is the best-performing Mercedes of all time doesn't do the SLS enough justice. It's more than that; it's actually a tour de force, one that's just a touch of refinement shy of competing with the best supercars. There is hope.

The SLS is the first model built from scratch by Mercedes' AMG performance division, which has tuned up many existing models and teamed with McLaren on the SLR. Though the SLR McLaren was formidable, I was never able to get over its electro-hydraulic brakes, a supposed innovation that also plagued the E- and SL-Classes until Mercedes reverted to conventional hydraulic brakes. The system definitely stopped the car quickly, but the pedal feel was so numb and difficult to modulate that I wouldn't accept it in a $10,000 car, much less one that cost a half-million dollars, even if it was someone else's money.

The SLS AMG's brake pedal didn't blow my mind, but it's more than acceptable, and the standard antilock brakes do a great job of halting this beast. If you're unsatisfied with the standard issue, go for the carbon ceramic brake option for a mere $12,500.

Of course, the SLS isn't about stopping. Like other models that have been sprinkled with AMG dust, its high point is how it goes. The SLS does zero to 60 mph in about 3.7 seconds, which is pretty much the cost of entry for anything claiming to be a supercar these days. Mercedes says the top speed is 197 mph. Though the torque rating is 479 pounds-feet, there's ample grunt at low revs to pin you to your seat from the word go. This engine sounds freakin' wonderful, with a bold growl on acceleration and some nice burbling to accompany engine braking. I'm sure they could eliminate the burble if they wanted to; I hope they don't.

Quick Engine, Sluggish Transmission

There's nothing quite like the sound of a 12-cylinder, but it's pretty easy to forget about all that when you hear the SLS AMG's 6.2-liter V-8. For the record, Mercedes calls this engine a 6.3-liter, even though the displacement is clearly listed as 6,208 cubic centimeters. (That's quite the round up.) Frankly, they should be boasting that they're squeezing 563 horsepower out of just 6.2 liters and eight normally aspirated cylinders in a class that relies on additional pistons and turbochargers. I don't know about physically, but technically they could throw some chargers on the thing and get even more output.

I'm less enthusiastic about the standard transmission, which is a dual-clutch automated manual, and not simply because it's not a stick shift. To dispense quickly with the requisite lament, it would be easy to charge Mercedes with a disdain for true manuals, but it's probably due to Mercedes buyers themselves; if not enough buyers opt for a manual, it's not worth offering one.

A dual-clutch is the right move, in theory, because this design allows for essentially instantaneous upshifts, lighter weight and better efficiency than a conventional automatic. The problem is that Mercedes' first attempt at the tech, called AMG Speedshift, needs a little work. If you take your foot off the brake and hit the accelerator immediately, the transmission pops the clutch quickly and you lurch forward. In time I learned to let off the brake, step lightly on the accelerator and wait a beat before giving it more gas. This allowed the clutch to feather in with no jerkiness. I adapted, but I don't think anyone should have to adapt to something labeled automatic — especially when other companies manage the transition with more grace.

While the transmission upshifts quickly, as advertised, I'm calling a technical foul because it doesn't always respond very quickly to driver inputs, even if you use the shift paddles on the steering wheel. Instantaneous shifts from 1st to 2nd, 2nd to 3rd, and so on shorten your zero-to- 60 sprints, but if there's a delay before it executes the shift after being called upon, the purpose is largely defeated.

I was also disappointed that the shift paddles don't override the automatic operation as some systems do — if only briefly — when you tap a paddle when barreling into a turn. In typical Mercedes fashion, pulling the minus paddle seems merely to lock out the highest gears — starting from the top, not from the gear you're in when you do it. For example, if you're in 4th and hit the downshift paddle repeatedly, it locks out 7th, then 6th, then 5th, etc. The only way to get full manual control is to turn the knob on the center console to the "M" setting. The other three transmission modes are automatic ones: "C" (Controlled Efficiency), "S" (Sport) and "S+" (Sport Plus). Each successively speeds the shift times and holds onto low gears farther up the engine-speed range. All but C also blip the throttle upon downshifting to match the revs.

None of the settings cured the underlying sluggishness, and the selector knob further frustrated attempts to downshift on the fly because a quick twist didn't jump from one of the automatic modes to M. If you turn the knob too quickly, it simply doesn't register.