The Z4 also incorporates some impressive new technological developments:

Optimized Smart Airbags. Both airbags have been further developed to optimize their inflated shape, deployment characteristics, and interaction with surrounding surfaces and components. The driver's-side airbag is notable for its compactness, fitting into the relatively small center hub of the standard sport steering wheel.

Active Knee Protection. As in the new 7 Series, two dedicated airbags are positioned below the dash and ahead of the driver's and passenger's knees. Because the airbags are normally in their uninflated state, they reduce the amount of space taken up by the knee protection, leaving space for features customers value. They also afford more effective knee protection, and allow finer "tuning" of other restraint systems (safety belts and front airbags).

New-technology side-impact sensors. By sensing pressure change within the door structure (rather than actual deformation as is conventional), these are able to trigger deployment of the side airbags very early in a side impact, yet minimize the chance of an unwanted deployment.

Passenger-airbag de-activation switch. To facilitate carrying a child in an approved infant seat, Z4s are standard-equipped with a disable switch for the passenger-side airbag. The switch requires a key to change over, and activates a "passenger airbag off" indicator on the console.

Rollover Protection. Between the reinforced A-pillars/windshield frame and the standard roll bars, the Z4 roadster has what it takes to maintain a "survival space" above its open cockpit.

ISIS, the Intelligent Safety and Information System. With the goal of tailoring the performance of safety systems more precisely to actual impacts, ISIS employs a considerably larger number of sensors than previous systems. Much of the progress on this front is due to faster, more powerful electronics and the use of fiber-optic cables that are not susceptible to extraneous electromagnetic disturbances. System software can be updated over the life of the vehicle; data useful to researchers can be retrieved from accident vehicles.