For enhanced safety, the front and rear seat shoulder belts of the Mercedes AMG C-Class Sedan have pretensioners to tighten the seatbelts and eliminate dangerous slack in the event of a collision. The Audi S3 doesn’t offer pretensioners for its rear seat belts.
Over 200 people are killed each year when backed over by motor vehicles. The AMG C-Class Sedan offers an optional Maneuvering Brake Function that uses rear sensors to monitor for objects to the rear and automatically applies the brakes to prevent a collision. The S3 doesn’t offer automatic braking for stationary objects directly to the rear.
The AMG C-Class Sedan has a standard Surround View System to allow the driver to see objects all around the vehicle on a screen. The S3 only offers a rear monitor and front and rear parking sensors that beep or flash a light. That doesn’t help with obstacles to the sides.
The AMG C-Class Sedan 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 S3’s blind spot costs extra.
To help make backing out of a parking space safer, the AMG C-Class Sedan has standard Rear Cross-Traffic Alert and Active Brake Assist automatically engages the brakes to help avoid a collision. Audi charges extra for Rear Cross-Traffic Assist on the S3.
The AMG C-Class Sedan’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 S3 doesn’t offer a driver alert monitor.
Both the AMG C-Class Sedan and the S3 have standard driver and passenger frontal airbags, front and rear side-impact airbags, driver knee airbags, side-impact head airbags, height adjustable front shoulder belts, four-wheel antilock brakes, all wheel drive, traction control, electronic stability systems to prevent skidding, crash mitigating brakes, daytime running lights and rearview cameras.
The Mercedes AMG C-Class Sedan weighs 554 to 1211 pounds more than the Audi S3. The NHTSA advises that heavier cars are much safer in collisions than their significantly lighter counterparts.