BMW recommends that only the tow fitting is used to tow the vehicle on to a flat bed, or if the X3 is used to tow another vehicle. They do not recommend connecting to any other part of the car.
In fact, there are no other parts of the car visible (to connect to) because of the full bottom cover except the lower suspension control arms. Towing the car with a strap attached to a control arm will almost certainly cause serious damage., and should be avoided unless it is a dire emergency. If an X3 must be towed, it should be on a flat bed ONLY. Towing with only two wheels elevated and two on the road will cause serious damage.
All X3's come with (1) tow eye-bolt. It is of a different size (longer and larger-diameter - coarser thread) than has been used on previous BMW's. The "new" X3 tow eye-bolt uses a tapered seat as opposed to the flat seat of the older version. It should be fully seated (fairly tight) before any use.
The widely available BMW,
"race-type" hinged tow rings will not fit.