Mercedes-Benz is giving its flagship roadster a power boost for the 2015 model year. The SL63 AMG's twin-turbocharged 5.5-liter V-8 gets a hefty 48-horsepower increase, bringing total output to 585 horsepower--matching that of the upcoming 2015 Mercedes-Benz S63 AMG coupe, and making both cars the most powerful vehicles yet to carry this particular engine.

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As well as the power boost, torque has risen by almost 74 pound-feet, bringing the already meaty total to over 664 pound-feet. As with all SLs, this is delivered to the rear wheels alone, though with an AMG limited-slip differential with up to 40 percent lock-up as well. AMG promises superior traction and improve lateral dynamics. Despite the power increase, fuel efficiency and emissions should be unaffected--not a priority for most buyers we expect, but its 19 mpg combined rating (16 mpg city, 25 mpg highway) should continue.

Among the wealth of options available on the SL63 AMG, buyers can now opt for carbon fiber engine covers for a little more glitz under the hood. U.S. pricing has not yet been announced but shouldn't change much from current levels. The new engine rating will make its debut in the 2015 Mercedes-Benz SL63 AMG, due this summer.


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