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UPDATE: Apparently this is an innovative use of a single clutch combined with the 7G-Tronic automated transmission (replacing the torque converter for startups), and not a dual clutch transmission. The MCT (Multi-Clutch Technology) acronym refers to a planetary (automatic) transmission’s multiple clutches and bands for each gear.

Mercedes-AMG GmbH finally gets more cogs than their usual 5-speed automatic with their new Mercedes-Benz SL 63 AMG. The 7-speed AMG SPEEDSHIFT MCT (Multi-Clutch Technology) uses a clutch to swap gears and moves off with a wet start-up clutch instead of a torque converter.

The AMG SPEEDSHIFT MCT 7-speed gearbox has 4 drive modes – C (Comfort), S (Sport), S+ (Sport plus), and M (Manual). Throttle response and shifts in comfort mode are “softer”, while in S mode shifts are faster and the clutches bite quicker. Shifts are approximately 20% faster than in Comfort mode, and for a further 20% speed improvement you can use S+. Using M mode, a further 10% is cut down for a total of 50% over the C mode – shifts only take 100 milliseconds in the M mode.

Downshifts in S, S+ and M modes use precise double-declutching and can downshift multiple gears, straight from 7th down to 3rd for example. This gives the drive a more sporty feel as the engine and exhaust sound great during double declutching, and also serves to minimize load-change reactions during downshifts.

The gearbox also has a Race Start function. It’s basically a way to get off the starting line with maximum acceleration, and everything including optimum launch revs, the launch itself, and then subsequent shifts are taken care of you, all the way to top speed.

This gearbox is only available in the new SL 63 AMG in which it is mated to a 6.3 litre normally aspirated V8, producing 525 horsepower at 6,800rpm and 630Nm of torque at 5,200rpm. The engine revs up to 7,200rpm, one of the more higher revving V8s around until BMW’s new V8 in the E90/E92 BMW M3 was unveiled.

The SL 63 AMG’s high performance sibling is the force inducted SL 65 AMG powered by a 6.0 litre twin-turbocharged V12 putting out a colossal 1,000Nm of torque and 612 horsepower. This engine is only paired with the 5-speed AMG SPEEDSHIFT, as I don’t think the AMG SPEEDSHIFT MCT or the Mercedes-Benz 7G-Tronic can take that huge amount of torque, and I don’t think many gears are needed with that amount of torque anyway. As it is the SL 65 AMG can go from 0 to 100km/h in 4.2 seconds.

More photos of the SL 63 AMG and SL 65 AMG after the jump.

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