The SMART airbag system on the BMW not only knew that both driver and front passenger were wearing their seatbelts, but it also realized what direction the crash was coming from and how severe it would be.
In its 1988 model year, Mercedes-Benz was first to introduce a dual-deployment threshold for its driver front airbag. The following year, a passenger front airbag was introduced with the same dual-deployment feature. Having the airbag deploy at higher or lower crash speeds is now common among automakers.
Besides knowing what speed the crash was occurring at, this early Mercedes system was smart enough to know if there were occupants in the front seats and if they had their seatbelts on at the moment of the crash. If the driver or front passenger were not wearing their seatbelt, for example, the smart airbag system would deploy their frontal airbag during a lower speed impact than if that same occupant were properly buckled up.