For enhanced safety, the front and rear seat shoulder belts of the Mercedes AMG S-Class 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 8 Series Gran Coupe doesn’t offer pretensioners for its rear seat belts.
For enhanced safety, the front seat shoulder belts of the Mercedes AMG S-Class 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 8 Series Gran Coupe doesn’t offer height-adjustable seat belts.
The rear seatbelts optional on the AMG S-Class inflate when a collision is detected, helping to spread crash forces over a much larger area of the body and limiting head and neck movement. This can help prevent spinal and internal injuries. The 8 Series Gran Coupe doesn’t offer inflatable seatbelts.
Over 200 people are killed each year when backed over by motor vehicles. The AMG S-Class has a standard Maneuvering Brake that uses rear sensors to monitor for objects to the rear and automatically applies the brakes to prevent a collision. The 8 Series Gran Coupe doesn’t offer backup collision prevention brakes.
To provide maximum traction and stability on all roads, All-Wheel Drive is standard on the AMG S-Class. But it costs extra on the 8 Series Gran Coupe.
Earlier warning of stopped traffic, traffic signals, dangerous road conditions, weather, or accidents, can keep driver's safer and prevent crashes. The AMG S-Class has Car-to-X Communication, a system that seamlessly communicates important warnings to the driver about impending danger, if they're available. The 8 Series Gran Coupe doesn’t offer a system that can receive automated systems from infrastructure or other vehicles.
The AMG S-Class 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 and moves the vehicle back into its lane. A system to reveal vehicles in the 8 Series Gran Coupe’s blind spot costs extra.
To help make backing out of a parking space safer, the AMG S-Class has standard Rear Cross-Traffic Alert and Rear Cross Traffic Brake automatically engages the brakes to help avoid a collision. BMW charges extra for Cross Traffic Warning on the 8 Series Gran Coupe and the 8 Series Gran Coupe’s Cross Traffic Warning does not include automatic braking.
Both the AMG S-Class and the 8 Series Gran Coupe have standard driver and passenger frontal airbags, front side-impact airbags, driver knee airbags, side-impact head airbags, 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, rearview cameras and driver alert monitors.
The Mercedes AMG S-Class weighs 889 to 1540 pounds more than the BMW 8 Series Gran Coupe. The NHTSA advises that heavier cars are much safer in collisions than their significantly lighter counterparts.