The 2012 Mercedes-Benz E63 AMG has been unwrapped at the New York Auto Show having gained a new, more economical lease on life thanks to the brand's 5.5-liter twin-turbo V8. For 2012, Mercedes-Benz is offering the mill in two levels of crazy, with either 518 horsepower in the regular E63, or 550 if you opt for the AMG sport package. That much grunt shuffles the standard car to 60 miles per hour in 4.4 seconds on to a top speed of 155 mph, or 4.3 seconds and 186 mph if you drop the extra coin for the sport pack.

Like its kissing but shapelier cousin, the CLS63 AMG, the 5.5-liter engine channels its substantial resources through AMG's Speedshift MCT seven-speed transmission. We've sampled and enjoyed the unusual gearbox before, and this one also has a "Controlled Efficiency" mode, which is Mercedes-speak for a stop-start function.

Despite the looney power and performance figures, Mercedes says its big sedan is 22 percent more efficient than last year's model, thanks to the new powerplant. To help keep things green(ish), the new heart sports spray-guided direct injection thanks to a set of piezo injectors. Mercedes has even gone so far as to develop an eco-friendly power steering setup which saves fuel by only drawing power when the wheel is being turned.

Inside, the car gets a new sports steering wheel with aluminum shift paddles and flat top and bottom sections. For those who go with the AMG sport package, the wheel is trimmed in Alcantara for the last word in racy luxury.