The passenger compartment of the X-Class remained stable in the frontal offset test.  Dummy readings showed good protection of the knees and femurs of the driver and passenger.  Mercedes-Benz demonstrated that a similar level of protection would be provided to occupants of different sizes and to those sat in different positions.  In the full-width rigid barrier test, protection of the driver and rear passenger was good or adequate for all critical parts of the body.  In the side barrier impact, protection of all critical body areas was good.  Even in the more severe side pole test, protection of the chest was adequate and that of other parts of the body was good.  Tests on the front seats and head restraints demonstrated good protection against whiplash protection in the event of a rear-end collision.  However, a geometric assessment of the rear seats indicated poor whiplash protection.  The standard-fit autonomous emergency braking system scored maximum points in tests of its functionality at the low speeds, typical of city driving, at which many whiplash injuries are caused.

In the frontal offset test, protection of the chest of the 6 year dummy was rated as marginal, based on chest decelerations.  Otherwise, protection of the 6 and 10 year dummies was good or adequate.  In the side barrier test, protection of both child dummies was good for all critical parts of the body.  The X-Class has a system that automatically disables the front passenger airbag when a rearward-facing child restraint is used in that seating position.  Mercedes-Benz showed that the system worked robustly and it was rewarded.  The restraint used to assess Group I ISOFIX restraints required a multi-stage installation procedure.  Otherwise, restraints could be properly installed and accommodated in the vehicle.

The protection provided by the bonnet to the head of a struck pedestrian was predominantly adequate or marginal.  Protection of pedestrians' legs was good or adequate.  The pedestrian-detecting autonomous emergency braking system performed well in Euro NCAP's tests, with collisions avoided or mitigated at most test speeds.

The X-Class has a standard seatbelt reminder system for the front and rear seats.  The speed assistance system identifies the local speed limit and provides this information to the driver who can then set the limiter accordingly.  A lane assistance system warns the driver when the vehicle is drifting out of lane.  The autonomous emergency braking system performed well at highway speeds, with collisions avoided or mitigated in all test scenarios.