The passive occupant protection systems, together with the "electronic crumple zone" and intelligent body design which have already been described, provide optimum protection potential, placing the M-Class at the top of its market segment. As part of this, a number of new deployment strategies are used. For example, the system can detect an impending rollover in the event of crash and if necessary deploy the head, side and window airbags, as well as the seat belt tensioners. Thanks to the new generously-sized side airbags and the window airbags with extended area of coverage, in the event of a crash the occupants can be more uniformly supported from the shoulder area down to the pelvic area, and thereby better protected. In side impacts too, the danger of injury is reduced thanks to extended coverage.

Additional protection potential is also provided for rear seat passengers with seat belt tensioners and force limiters on the outer seat positions. The integration of optional thorax bags in the tilt-adjustable folding seat backrests enables optimum airbag positioning for each backrest position. The components of the passive occupant protection systems include:

Two-stage adaptive airbags for the driver and front passenger
Kneebag for the driver
Sidebags for driver and front passenger (combined thorax/pelvis bags)
Sidebags in the rear row of seats as an option
Windowbags across both rows of seats from the A to the C-pillar
3-point seat belts on all five seats
Pyrotechnic reel tensioners and permanent belt force limiters as well as electrically reversible belt tensioners in the front, reel tensioners and single-stage force limiters for the outer seats in the rear
ISOFIX child seat anchorage
Belt height adjustment for the driver and front passenger
Belt status display for rear-seat passengers in the instrument cluster Automatic child seat recognition (optional) with deactivation of the front passenger airbag if a special Mercedes-Benz child seat is used in a rear-end collision, a passive head restraint system developed specifically for this purpose can reduce the forces exerted on occupants