This paper summarizes the work done on air bag systems under Volkswagen's restraint system development program.The paper first presents theoretical considerations, both generally and then specifically applied to small cars. Based on this, some typical design parameters for the Volkswagen air bag systems are given.Then, sensor considerations and various air bag system concepts and configurations are discussed. The solutions chosen for the VW are presented, followed by some typical test data from sled tests and full scale crash tests.It is also pointed out that acceptable small-car systems cannot be expected simply by scaling down large car systems, mainly because of the differences in vehicle deceleration characteristics and passenger compartment layout between large and small cars. Volkswagen's development experience over the last few years has shown that, before solving all the peripheral problems of inflatable restraints which are not covered by FMVSS 208, an extensive development effort is required to reach the basic 30 mph performance levels attained by large car air bag systems one or two years ago.In summary, the advantages and disadvantages of the air bag system are described. These indicate that the air bag is not clearly superior to other restraints, and Volkswagen believes that the consumer should be allowed to select the type of restraint system for his vehicle.