The passenger compartment of the G-Class remained stable in the frontal offset test. Dummy readings indicated good protection of the knees and femurs of the driver and passenger. Mercedes-Benz showed that a similar level of protection would be provided to occupants of different sizes and to those sitting in different positions. Chest compression in the driver dummy indicated weak protection of this body region. In the full-width rigid barrier test, chest protection was marginal for the driver's chest but was good for all other critical body areas. For the rear dummy, dummy readings of chest compression indicated marginal protection. However, a high load in the shoulder belt pointed to a risk of injury which the dummy is not able to measure, and protection of the chest was penalised and downrated to 'weak'. In both the side barrier test and the side pole impact, protection of all critical body areas was good and the G-Class scored maximum points. Tests on the front seats and head restraints demonstrated good protection against whiplash injury in the event of a rear-end collision. A geometric assessment of the rear seats indicated marginal whiplash protection. The standard-fit autonomous emergency braking (AEB) system performed well in tests at the low speeds, typical of city driving, at which many whiplash injuries are caused.

In the frontal offset test, dummy readings of neck tension in the 10-year dummy indicated poor protection of this body area. Otherwise, protection was good. For the 6-year dummy, protection of the neck was marginal. In the side barrier test, protection of both child dummies was good. The front passenger airbag can be disabled to allow a rearward-facing child restraint to be used in this seating position. Clear information is provided to the driver regarding the status of the airbag and the system was rewarded. All of the restraint types for which the G-Class is designed could be properly installed and accommodated.

The protection provided by the bonnet to the head of a struck pedestrian was marginal or adequate over most of its surface, with areas of good and poor performance. Protection of pedestrian's legs was good or adequate, as was the protection offered to the pelvis. The AEB system can detect pedestrians and cyclists, as well as other vehicles. The system performed well when tested for its reaction to vulnerable road users such as these.

The AEB system gave generally good results in tests of its functionality at highway speeds. The car has a lane assistance system which helps prevent inadvertent drifting out of lane but can also intervene in some more critical situations. The speed control system uses digital mapping combined with a camera to identify what the local speed limit is and to inform the driver, who can then set the limiter to the appropriate speed. A seatbelt reminder is standard for front and rear seats.