Both the Cullinan and X5 have child safety locks to prevent children from opening the rear doors. The Cullinan has power child safety locks, allowing the driver to activate and deactivate them from the driver's seat and to know when they're engaged. The X5’s child locks have to be individually engaged at each rear door with a manual switch. The driver can’t know the status of the locks without opening the doors and checking them.
To provide maximum traction and stability on all roads, All-Wheel Drive is standard on the Cullinan. But it costs extra on the X5.
A passive infrared night vision system optional on the Cullinan helps the driver to more easily detect people, animals or other objects in front of the vehicle at night. Using an infrared camera to detect heat, the system then displays the image on a monitor in the dashboard. The X5 doesn’t offer a night vision system.
Both the Cullinan and the X5 have standard driver and passenger frontal airbags, front side-impact airbags, driver and front passenger knee airbags, side-impact head airbags, front seatbelt pretensioners, four-wheel antilock brakes, traction control, electronic stability systems to prevent skidding, crash mitigating brakes, post-collision automatic braking systems, daytime running lights, lane departure warning systems, blind spot warning systems, rearview cameras, rear cross-path warning and driver alert monitors.
The Rolls-Royce Cullinan weighs 1041 to 1486 pounds more than the BMW X5. The NHTSA advises that heavier vehicles are much safer in collisions than their significantly lighter counterparts.