AMG was a strange claim to the San Francisco debut of the all new pint-sized speedster, the SLK 55 AMG. "It may be the most efficient performance of the car is very good in the world." Huh? I like the odd statement, because if this car is actually the "most efficient performance of the car in the world," Mercedes-Benz would sure as the sun rises trumpet that fact until the cows believed it. But what if the SLK 55 AMG sports car is really the most efficient of all? Well, good job, AMG. Only a few years ago, such a statement is laughable at a press briefing AMG. Think of the horsepower wars? The 6200-plus cubic inch engines goosed within an inch of thermal meltdown? These days, however, we are plausible. With a new corporate focus on reducing CO2 emissions 40 percent by 2015, it very well might even be true.

With that out of the way, meet the newest baby roadster sports an AMG badge - the most powerful ever (and I will argue best looking) SLK 55. While there are other bits and pieces that an AMG, at the end of all the noise (! And the 44-page press release), Mercedes-Benz in-house tuning arm is really all about one thing: big engine pumps out big band -shredding power numbers. The new SLK 55 is no exception, albeit a little different. Under the long hood is a special version of the AMG 5.5-liter V-8 (internal code name: M157). Only thing is, the two turbochargers and intercoolers are removed "packaging reasons." In their place? Nada. But do not worry, as the new (and newly baptized) M152 engine puts 422 horsepower and a fairly healthy 398 lb-ft of torque.

Think of the power figures for a moment. The outgoing, but still available in the C63 AMG (SLS Gullwing and supermodel) M156 6.2-liter V-8 cranks out 451 horsepower and 443 lb-ft of torque. The new engine will lose seven tenths of a liter in displacement, but the most important metric horsepower per liter, actually increases (by about 73 hp per liter to 77). For those keeping track, the torque per liter rate also increases, from 71 to 72 lb-ft. However, compared to the old 355 hp SLK 55, the new man is a monster. Perhaps even more important to roadster fans is that since the turbos are picked, the SLK 55 AMG sounds better than the other equipped with the M157 mill. You can actually hear the exhaust, and a lot of good back lip. Especially with the top removed and stored and the new sport exhaust burbling / screeching away.

And should you choose to fold and let the metal roof, you can breathe easier knowing that the new car puts 30 percent less CO2 than the previous version. It's also much more efficient in terms of miles per gallon, and to achieve that feat, AMG had the car put his full bag of tricks fuel-sipping. First and foremost is a smooth cylinder deactivation system that is (almost) completely unnoticeable. If you really go out of your way to feel and listen to it, you'll discover a slight (and I mean slight) tremble when the other four cylinders fire and the engine is running again in a good V-8. But in reality, the reactivation feels like a small bump in the road. The M152 also employees under high pressure direct injection (2900 psi), a high compression ration of 12.6:1, and start / stop technology. Now you have the AMG DRIVE selector in C (or Eco) mode to take advantage of both the start / stop and leave the cylinder off. And most of the time, most people probably do just that. The end result will net you about 28 mpg combined. Better yet, the car feels mighty fast, especially with the top down.

Should you choose to set the knob turn right and good things happen when the fast-ish seven-speed switching slides in Sport mode. Shifts are not only faster, but under aggressive braking transfer fires a number of beautiful downshifts. Hold the knob and you get full manual mode where you find the Mercedes gearbox almost - but not quite - as good as a similar double clutch. There is also a new torque-vectoring braking and understeer that the brakes on the rear right individual detects counteract the bad behavior. Fortunately for the driver, the SLK 55 is not too much understeer to start, so you probably will not notice that last feature to activate. I've shown a few times, and while it works, I still do not like the idea of using brakes to go faster. It's more a philosophical problem than a real one. The cars I drove were equipped with optional AMG package handling that stiffer a stiffer suspension setup, a locking rear differential, upgraded brakes and features. The result of all this new technology in the treatment is good.

Description of a beautiful twisted road near Santa Cruz, I was overwhelmed by the large bore unmistakable growl of a full-blown SLS AMG. Behind me in a white SLS Roadster were some PR peeps of MB. And when I say behind me, I mean I could hear their stereo braking zones (they were blasting Donna Summers, if you're interested). And for 30 miles, the two cars had. They had more power, but I learned to drive in California twisted canyons, so the two cars seemed well matched. I had to drive hard, but I managed to stay in front of the car much faster, especially if the road more and more complicated. The rapid run showed me the new SLK 55 AMG can handle well, even with a drop top. Hood and other typical convertible shake bad habits are minimized, so admirable. In fact, a much more talented than I was reporter to me that the new SLK 55 is a great drift machine in the paddock at Laguna Seca. Many of our German friends' grief. At the end of all this, the SLK 55 AMG is just definitely fun to drive. An important feature for people who are in the market for a small, fast and environmentally friendly roadster with almost no luggage she will likely return at least $ 75,000 - but many of them there are.