Over 200 people are killed each year when backed over by motor vehicles. The M3 offers optional Active Park Distance Control that uses rear sensors to monitor and automatically apply the brakes to prevent a rear collision. The RS 3 doesn’t offer backup collision prevention brakes.
The M3 offers an optional Surround View to allow the driver to see objects all around the vehicle on a screen. The RS 3 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 M3 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 RS 3’s blind spot costs extra.
To help make backing out of a parking space safer, the M3 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 RS 3.
The M3’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 RS 3 doesn’t offer a driver alert monitor.
Both the M3 and the RS 3 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 and rearview cameras.