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.
Over 200 people are killed each year when backed over by motor vehicles. The Cullinan has standard Active Park Distance Control that uses rear sensors to monitor for objects to the rear and automatically applies the brakes to prevent a collision. The Cayenne Coupe doesn’t offer backup collision prevention brakes.
The Cullinan’s standard lane departure warning system alerts a temporarily inattentive driver when the vehicle begins to leave its lane. A lane departure warning system costs extra on the Cayenne Coupe.
The Cullinan has a standard blind spot warning system that uses sensors to alert the driver to objects in the vehicle’s blind spots where the side view mirrors don’t reveal them. A system to reveal vehicles in the Cayenne Coupe’s blind spot costs extra.
To help make backing out of a parking space safer, the Cullinan has standard Cross Traffic Warning, helping the driver avoid collisions. Porsche charges extra for rear cross-path warning on the Cayenne Coupe.
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, rearview cameras and available night vision systems.
The Rolls-Royce Cullinan weighs 628 to 1651 pounds more than the Porsche Cayenne Coupe. The NHTSA advises that heavier vehicles are much safer in collisions than their significantly lighter counterparts.