The Cullinan’s pre-crash front seatbelts will tighten automatically in the event the vehicle detects an impending crash, improving protection against injury significantly. The Cayenne Coupe doesn’t offer pre-crash pretensioners.
Both the Cullinan and Cayenne Coupe 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 Cayenne Coupe’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.
The Cullinan’s driver alert monitor detects an inattentive driver then sounds a warning and suggests a break. According to the NHTSA, drivers who fall asleep cause about 100,000 crashes and 1500 deaths a year. The Cayenne Coupe doesn’t offer a driver alert monitor.
Both the Cullinan and the Cayenne Coupe have standard driver and passenger frontal airbags, front side-impact airbags, driver and front passenger knee airbags, side-impact head airbags, four-wheel antilock brakes, all wheel drive, 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 available night vision systems.
The Rolls-Royce Cullinan weighs 582 to 1574 pounds more than the Porsche Cayenne Coupe. The NHTSA advises that heavier vehicles are much safer in collisions than their significantly lighter counterparts.