In the past twenty years hundreds of infants and young children have died after being left in vehicles, usually by accident. When turning the vehicle off, drivers of the 4 Series Gran Coupe are reminded to check the back seat if they opened the rear door before starting out. The S3 doesn’t offer a back seat reminder.
Over 200 people are killed each year when backed over by motor vehicles. The 4 Series Gran Coupe offers an optional Active Park Distance Control 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 4 Series Gran Coupe offers an optional Surround View 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 4 Series Gran Coupe 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 S3’s blind spot costs extra.
To help make backing out of a parking space safer, the 4 Series Gran Coupe has standard Cross Traffic Warning, helping the driver avoid collisions. Audi charges extra for Rear Cross-Traffic Assist on the S3.
The 4 Series Gran Coupe’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 4 Series Gran Coupe and the S3 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, 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 all wheel drive.