For enhanced safety, the front seat shoulder belts of the Porsche Cayenne are height-adjustable to accommodate a wide variety of driver and passenger heights. A better fit can prevent injuries and the increased comfort also encourages passengers to buckle up. The BMW X3 M doesn’t offer height-adjustable seat belts.
Both the Cayenne and X3 M have child safety locks to prevent children from opening the rear doors. The Cayenne 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 X3 M’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 Cayenne has standard Maneuver Assist that uses rear sensors to monitor for objects to the rear and automatically applies the brakes to prevent a collision. The X3 M doesn’t offer backup collision prevention brakes.
A passive infrared night vision system optional on the Cayenne 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 X3 M doesn’t offer a night vision system.
Both the Cayenne and X3 M have rear cross-traffic warning, but the Cayenne has Rear Cross Traffic Alert (automatically applies the brakes) to better prevent a collision when backing near traffic. The X3 M’s Cross Traffic Warning doesn’t automatically brake.
Both the Cayenne and the X3 M 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, 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 driver alert monitors.