For enhanced safety, the front and rear seat shoulder belts of the Audi S8 have pretensioners to tighten the seatbelts and eliminate dangerous slack in the event of a collision and force limiters to limit the pressure the belts will exert on the passengers. The BMW M8 doesn’t offer pretensioners for its rear seat belts.
For enhanced safety, the front seat shoulder belts of the Audi S8 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 M8 doesn’t offer height-adjustable seat belts.
Both the S8 and M8 Gran Coupe have child safety locks to prevent children from opening the rear doors. The S8 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 M8’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 S8 has a standard front seat center airbag, which deploys between the driver and front passenger, protecting them from injuries caused by striking each other in serious side impacts. The M8 doesn’t offer front seat center airbags.
Earlier warning of stopped traffic, traffic signals, dangerous road conditions, weather, or accidents, can keep driver's safer and prevent crashes. The S8 has Car-to-X Services, a system that seemlesly communicates important warnings to the driver about impending danger, if they're available. The M8 doesn’t offer a system that can receive automated systems from infrastructure.
A passive infrared night vision system optional on the S8 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 and even aims one of the vehicle’s headlights in the direction of the person or object. The M8 doesn’t offer a night vision system.
Both the S8 and M8 offer rear cross-traffic warning, but the S8 with Rear Cross-Traffic Assist also has Automatic Brake Activation (automatically applies the brakes) to better prevent a collision when backing near traffic. The M8’s Cross Traffic Warning doesn’t automatically brake.
Both the S8 and the M8 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, rearview cameras and available blind spot warning systems.
The Audi S8 weighs 566 to 831 pounds more than the BMW M8. The NHTSA advises that heavier cars are much safer in collisions than their significantly lighter counterparts.