A method for controlling a passenger restraint system aboard a motor vehicle includes receiving, via a controller, biometric vulnerability classifier signal(s) indicative of vulnerability characteristics of a passenger seated in an interior of the motor vehicle. In response to the biometric vulnerability classifier signal(s) and a detected vehicle event requiring an actuation of the passenger restraint system, the method includes automatically adjusting an actual capacity setting of the passenger restraint system via the controller. A motor vehicle includes a vehicle body defining a vehicle interior, a passenger restraint system positioned in the vehicle interior; and a controller operable for controlling the actual capacity setting of the passenger restraint system in accordance with the method. The passenger restraint system may include a seatbelt, a seat, and one or more airbag systems.