Official press release:

"Mercedes AMG Unveils S 63 AMG and CL 63 AMG
Stuttgart, 07/25/2001 - Mercedes-AMG GmbH is presenting two top-of-line luxury models that will set new standards in handling and performance. Known as the S 63 AMG and CL 63 AMG, the models are powered by a newly developed V12 engine, whose impressive torque and performance will guarantee a first-class driving experience. A displacement of 6,258 cubic centimeters provides the engine with 326 kW/444 hp of output and a maximum torque of 457 pound-feet. These outstanding figures give the cars unmatched performance, allowing the Mercedes-Benz CL 63 AMG to accelerate from 0-60 mph in just 5.5 seconds, and the S 63 AMG in 5.7 seconds. The top speed for both models is 155 mph (electronically regulated). However, both high-performance automobiles can be delivered without any speed regulator if desired."

Now this was pretty unexpected. I'm guessing that the S55 and CL55 will continue on. Now we have a AMG tuned V-8 and AMG tuned V-12 in the lineup. A couple of months ago, Car and Driver tested a S600. It went from 0-60 in 5.3 seconds. That's really fast for an S-class. The S55 is even faster, and the S63 will be faster than the S55 (0-60 5.7? Probably an estimate, it will do better). Its amazing what MB has done with the S-class. It is truly one of the best cars ever made.