Mercedes-Benz's latest line of 6.3-badged cars--the S63 among them--are actually powered by 6.2-liter engines, so perhaps it's not surprising that Mercedes is planning to keep the '63' naming convention despite replacing the engine with a new turbocharged 5.5-liter V-8.

The new M157 5.5-liter turbo V-8 beats the 6.2-liter engine's output with 536 horsepower and 590 pound-feet of torque, all while yielding 25 percent better fuel economy, so it will only be hardcore nomenclaturists that bother complaining over the badging. Just think of it as Lexus-like (or BMW-like) badging to match the "virtual" displacement of the car. Despite the less-thirsty attitude, the big sedan is expected to shoot to 60 mph in 4.4-4.5 seconds.

Thanks to its turbocharged power, the new S63's torque curve will be flat from 2,100 rpm through to 4,600 rpm, meaning punchy mid-range acceleration. For those that prefer a bit more bite, the performance package narrows down the peak torque plateau to 2,400-3,600 rpm while providing 563 horsepower and 664 pound-feet of torque.

A new version of Mercedes' MCT 7-speed automatic transmission will get the nod for the new 2011 S63, with the revisions focused primarily on fuel savings.

The 2011 Mercedes-Benz S63 will make its debut in the third quarter of the year, with the M157 engine spreading to the other '63'-badged cars through the end of 2010 and beginning of 2011.