The rear seatbelts optional on the 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 S8 doesn’t offer inflatable seatbelts.
The S-Class’ standard pretensioning seatbelts also sense rear collisions and remove slack from the seatbelts to help protect the occupants from whiplash and other injuries. The S8 doesn’t offer a whiplash protection system.
Over 200 people are killed each year when backed over by motor vehicles. The S-Class has standard Maneuvering Brake Function that uses rear sensors to monitor and automatically apply the brakes to prevent a rear collision. The S8 doesn’t offer backup collision prevention brakes.
The S-Class has a standard blind spot warning system which 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 S8’s blind spot costs extra.
To help make backing out of a parking space safer, the S-Class has a standard rear cross-path warning system, which uses sensors in the rear bumper to alert the driver to vehicles approaching from the side, helping the driver avoid collisions. Rear cross-path warning costs extra on the S8.
The S-Class’ 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 S8 doesn’t offer a driver alert monitor.
Both the S-Class and the S8 have standard driver and passenger frontal airbags, front and rear side-impact airbags, driver knee airbags, side-impact head airbags, front seatbelt pretensioners, height adjustable front shoulder belts, four-wheel antilock brakes, all wheel drive, traction control, electronic stability systems to prevent skidding, crash mitigating brakes, post-collision automatic braking systems, lane departure warning systems and around view monitors.