The new 2011 BMW X3 hasn't yet been crash-tested or rated for safety by either of the major U.S. agencies. The last-generation X3 wasn't tested by the federal government, though it did do well in IIHS tests, with top 'good' frontal and side-impact ratings.
Standard safety features on the 2011 X3 include all the usual airbags, active front head restraints, anti-lock brakes, and stability systems. In Sport mode, drivers of a navigation-and-iDrive-equipped X3 can customize that Sport mode for differing levels of stability control. A stability-control mode with a higher threshold of intervention also aids traction and confidence in snow.