All X5 built after week 40 in 2008 will have the Efficent Dynamics. It will increase the the fuel efficency of the 4.8i very well (6% savings). On the 3.0si there will be not to much savings (5%). These numbers are done by the ECE cycle test (European Style). The diesels are improved by 7% ... by the way.

Hope that helps

Regards

Christian