The new CDIs engines are terrific. They deliver a fanstastic power (for a diesel engine of course) and a incredible torque.
For example, the S400 CDI deliver 250hp and about 420 lb/feet
at only 1700 rpm. The max speed is electronically limited at 155 mph (not usual for a diesel !!) and the 0-60 mph only require 7.8s. Presently, the S400 CDI is the best diesel sedan in the world (maybe not for a long time because the new VWPhaeton and its 313hp V10 diesel engine will arrive soon).

The other CDIs engine are also very good with still a lot of low-end torque which make them very easy to drive and don't require to downshift often (you can go up a hill without downshift !!). The fuel cost of this CDI powered car is very low regarding their very good performances. The average fuel consumption is about 34mpg (without drive like a snail !). This engines are also very smooth to drive and very quiet. Thanks to the variable geometry turbocharger the engine provide a lot of power since the the low rotations (about 1200rpm) and you don't feel the lack of power below 2000rpm caracteristic of the old turbocharged diesel engines.

Presently, the range of CDIs engines is :
2.2 L4 115hp
2.2 L4 143hp
2.7 L4 168hp
3.2 L6 197hp
4.0 V8 250hp.

A new V6 CDI 3.2 is in development (in order to powered the new
E class).

So, the new CDIs engines are more efficient than the older and "classic" engines (there is no comparison possible).
The only inconvenience of this engine is that they require a diesel fuel of a very good quality (no sulfur, absolutely 0.000 % of water within otherwise all the injection system can jammed and it's very very expensive to replace).
Probably those engines will be less reliable than their ancestors due to their high technology but what a fun to drive
those cars !

By the way, does anyone know why the CDIs models are not
sold in the US ?

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in France : 240D 1981 380 000 km
240D 1984 252 000 km
300D 1978 325 000 km
in the US : Ford Tempo 1993 70K