The rear area too of the M-Class also protects the sturdy passenger compartment in crash situations thanks to specific deformation work, therefore minimising the loads on the occupants. A special impact test conducted to check tank leakage gives an indication of the exceptional load capabilities of the rear part of the Mercedes-Benz M-Class body. The test involved running a crash carriage into the rear of the M-Class at 80 km/h. The tank system survived this fatal impact without suffering any leaks.

To enhance rigidity, increase the energy absorbtion capability and improve deformation behaviour, the multi-piece rear longitudinal members feature a continuous closed cross-section with stepped plate thicknesses (tailored blanks). The spare wheel well forms an integrated part of the steel floor, and a steel flexible bumper bracket carries the rear bumper covering and is connected to the rear structure via two steel crashboxes.