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      02-21-2014, 11:45 PM   #17
First Lieutenant

Drives: 2011 E93 M3 Jerez Black/Black
Join Date: Sep 2011
Location: San Diego, CA

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AMG uses cylinder deactivation on the current SLK55. The M152 engine is exclusive to that model and it's part of the AMG2015 "Road to Sustainability" campaign. Naturally aspirated 415 hp/398 lb ft torque. 19/28 fuel economy - which is obviously good for an 8-cylinder. It's basically the current engine used in the AMG 63s without turbochargers.

Originally Posted by Ezio View Post
whats funny is that people hate that Cylinder Deactivation. reason: when you have a exhuast, your car will sound like a 4 banger at times. (tunes can turn this off)
The SLK55 does have a drone in 4-cylinder mode, but cylinder deactivation can be turned off with start/stop.

Originally Posted by jphughan View Post
Apparently it was very difficult for GM to get the transitions between cylinder modes to occur smoothly, especially with a manual transmission involved, so I wouldn't call it an easy way to get a benefit.
Obviously MB doesn't offer automatics but they had to use the 7-speed AMG SPEEDSHIFT (which is not the current tranny in most AMGs) to provide smooth shifting between modes rather than a DCT like in the latest AMGs.

Originally Posted by dreamspeed View Post
I'm probably totally off but doesn't the 4 cylinders have to move 8 cylinders worth of engine still ?
The SLK55 still makes 170 lb ft of torque in 4-cylinder mode in a car only weight 3500 lbs. It switches between modes in 30 milliseconds if it senses greater load and it feels seamless. The only way you'd really notice is the sound of the engine and the mode indicator on the dash.

Long-story short, I agree with OP...I'm surprised this technology isn't more prevalent and although it requires some compromises it still is a viable option even in a performance car.