You're probably thinking about the full size two door CL 65 coupe or the monster 4 door S 65 sedan. Both of them have the same drivetrain.
Don't confuse them with the 600s. That's a 5.5 liter twin turbo V12 putting out a mere 500 hp. AMG took that motor and tweaked it to over 1,000 ft/lbs of torque but it was hell on the transmission. They backed it down to 738 ft/lbs and gave it a warranty.