Active steering was never offered on the E53 guys.......

For those who don't know what's so special, AS actually alters the steering ratio based on vehicle speed. For example at parking lot speeds, turning the steering wheel about 90 degrees in each direction you'd be turning full-lock. At high speeds, the same 90 degree turn in the steering wheel translates to very little change in wheel angle. For an SAV, this is something pretty handy IMO. (Don't really need it as much on a E60 or E90).

You might be thinking of Servotronic, which just varies power steering assist based on vehicle speed, and was a $250 option on X3s and I guess later X5s. The standard steering on X3s and E53 X5s was a engine-speed dependent assist, which varies assist based on rpm.