can I disengage the 4wd to get better mileage? on 2001 BMW 330xi

I am currently getting around 17miles per gallon,and cannot afford 55.00 everytime I fill up,which currently is about once a week.

Asked by for the 2001 BMW 330xi
No. The x-drive is a complex system with an intelligent traction control. No disengagement is possible without turning most of the warning lights on and getting systems going into limp home mode.
If you want the best possible gas mileage make sure the engine is 'tuned up', filters are clean and tire pressures are correct.
The manufacturer also recommends to replace the O2 sensors at 100K miles.

1 more answer
in a word, no.