Open Letters to Cadillac Corporate Discussion, What about the 2.9 V6 and 4.5 V8 TD? in Item Specific Cadillac Discussion; With those two engines it would be well possible to get settled in Europe!
Why the major delay?
Competition like ...
Possible GM cars that could sport a 3.0L Turbo diesel in Europe:
Insignia (opposed to Citroen C5, Audi A4, VW Passat, BMW 3-series)
Antara/Captiva (opposed to VW Tiguan, Audi Q5, BMW X3/X1)
SRX (opposed to Audi Q5/Q7, BMW X5, VW Touareg)
CTS (opposed to BMW 5, Mercedes E, Audi A6/A5, VW Phaeton)
XTS (oposed to Audi A8, Mercedes S, BMW 7)
LaCrosse or an Opel premium version (opposed to Audi A6, VW Phaeton)