http://www.autoblog.com/2008/02/08/o...3-and-sl65-am/
MCT Transmission – The Best of Both Worlds
Providing the direct feedback of a manual transmission with the total convenience of an automatic, the new seven-speed MCT with AMG Speedshift is an all-new design available only in the new SL63 AMG. Featuring seven speeds, four shift modes and a double-clutching function, the MCT transmission offers impressive versatility and even faster shift times.
At the heart of the new AMG Speedshift MCT seven-speed sports transmission is a new start-up clutch, which runs in an oil bath and replaces a conventional torque converter. Thanks to its low rotational mass, the start-up clutch helps the transmission respond instantaneously and dynamically with no slip.
Fitted with four drive modes: "C" (Comfort), "S" (Sport), "S+" (Sport plus) and "M" (Manual), the transmission provides customized shift control for maximum driving pleasure, and does so with no interruption of power. In Comfort mode, smooth shifts coupled with a "soft" accelerator response are set up for silky smooth power transfer. In Sport mode, the engine and transmission interact quicker – upshifts and downshifts take place at higher engine speed. Gearshifts are around 20 percent faster than in Comfort mode. Switching to the Sport Plus mode cuts another 20 percent off shift times, while the sportiest mode, Manual, reduces shifting times by another 10 percent – a total reduction of 50 percent compared with Comfort mode. In Manual mode, the gearshifts take just 100 milliseconds.
Ultra-fast, spontaneous multiple downshifts are another forte of the new MCT sports transmission. For instance, kickdown will shift directly from seventh down to fourth gear or from fifth to second. In the "S" (Sport), "S+" (Sport plus) and "M" (Manual) modes, an automatic double-clutching function is active. Every manual or automatic downshift is accompanied by precisely metered double-clutching – from "S" through "S+" to "M" incrementally. Not only does double-clutching make driving more fun, but virtually load-free downshifting minimizes any jerking, a special benefit when braking into a curve.