Helping that trick new engine out is Mercedes' tried-and-true seven-speed automatic transmission. While enthusiasts will appreciate its rev-matching on downshifts and refusal to upshift automatically while in "Manual" mode, the average owner will likely better appreciate the new Controlled Efficiency, or "C" mode. In C mode, the computer will soften accelerator response and start the car in second gear to minimize fuel burn. In fact, drive it gently enough and you'll be in sixth gear by 37 mph with the computer relying on the engine's massive torque to keep things smooth. What's more, C mode also automatically enables a new Stop/Start function that will turn off the engine while at a stop, so long as the engine temperature, battery charge and your interior climate settings are all where they're supposed to be. As soon as you take your foot off the brake, the engine will fire back up. Sport and Manual mode both deactivate the feature, and it can be switched off in C mode as well. Combined with an alternator that only charges on overrun and braking and you've just squeezed a bit more efficiency out of your car.
The CL65 AMG's updates aren't quite as involved. The massive 6.0-liter V-12 gets a new set of turbos that now crank out up to 22 psi of boost, ramping up the power from 604 horsepower in the last model to 621 horsepower in the new car. Torque is still limited to 738 pound-feet even though the engine is capable of producing 885 pound-feet, which is simply too much for the drivetrain to handle. In fact, the CL65 AMG must continue to make-do with Mercedes' Speedshift five-speed automatic transmission because the seven-speed dual-clutch box can't handle the power.
Those 17 extra ponies are good for an extra 0.3 seconds in the sprint to 60 mph, running it in a claimed 4.2 seconds before topping out at a limited 186 mph. Refinement in the engine and tricks like the alternator that only charges on overrun and braking help the CL65 AMG increase its fuel economy an unspecified amount while dropping CO2 emissions by 3.5 percent.
Both cars get the full bag of tricks from the new CL-Class. That means Direct Steer, a lighter, more direct steering system, Torque Vectoring Brake, which can brake the inside rear wheel to kill understeer, and Automatic Crosswind Stabilization are all standard. The AMG cars also pick up the CL-Class' Active Lane Keeping Assist, Active Blind Spot Assist, Night View and Drowsiness Detection systems along with Active Body Control.