The 2015 Ford Mustang has a different type of knee airbag on the passenger side. The bag is an injection-molded plastic bladder that’s sandwiched between the inner and outer glove box door panels. When the vehicle is in an accident, and an impact is detected, the bladder is inflated, pushing the flexible outer panel straight forward toward the passenger’s legs. When their legs hit the panel, the force of the impact is evenly distributed across it, while also being absorbed by the bladder. The inflator is about 75 percent smaller than that used by a regular knee airbag.