German Car Zone

Acutally ABC is standard on all CL and V8 and up SL models and 600/63/65 models of the S-Class.

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According to MBUSA, "Active Body Control (ABC) uses a system of sensors and electronically controlled high-pressure hydraulics to instantly counteract the forces of vibration, pitch, dive, squat, and roll. Setting ABC to 'Sport' mode virtually eliminates body roll in cornering."

The CL550/CL600 has 2 settings, C-Comfort (comfort driving), S-Sport (standard driving). The CL63 has a thrid setting, M-Manual, where gear selection is only changed by use of the paddles, overiding the automatic transmission entirely. In the CL63, the C-Comfort is for standard driving and S-Sport is for sport driving. At each level of change from C to S to M, the ABC suspension firms up to a very firm ride in M-Manual mode. The shifting points also change substantially in the S-Mode, providing a very aggressive automatic in both upshifting and downshifting.

there has never been a CL with the Airmatic suspension, not since 1999--and even before, I do not know surely.

I see ABC described incorrently on so many reputable British and American car magazines, that sometimes I wonder how these automotive writers can be so shallow in their research and knowledge.
ABC is not the air-based suspension that the S Class has. It is hydraulic, but it has regular steel shocks and struts. Which is why the ride can be harsher in most settings. However, Airmatic when in its hardest setting (from 2002 S500 experience) is much harsher than ABC in its two light position. ("05 S600)

Ok guys there is a update on Clarkson's review on the CL. This is what he said

from Jeremy Clarkson Dodge Grand Caravan review | Driving - Times Online

He mentioned about the CL at the bottom of the article.

Wait a second, so the CL doesn't have air suspension at all? Any reason for this?

ABC = Active body control
Airmatic = Air suspension

ABC is superior at controlling body movements/lean in corners whereas airmatic can provide the ultimate in ride quality.

I think top of the range S-classes use ABC as well.

very entertaining read.....

That is right!! The ABC is still working with hydraulic oil! But you also have the possibility to change the response characteristic of the suspension.

Here is a link to the "Mercedes TechCenter", where they describe how the ABC works:
Mercedes-Benz TechCenter