One problem related to air bag not deploy has been reported for the 2013 BMW X5. The most recently reported issues are listed below.
During frontal impact at 34+mph, airbag did not deploy; driver hit steering wheel and passed out; brakes did not function properly either (was serviced by BMW dealership less than 2 months ago); vehicle slid straight into car in front of it and brakes did not engage properly with driver pressing brake petal.