Over 200 people are killed each year when backed over by motor vehicles. The 4 Series Convertible offers optional Active Park Distance Control that uses rear sensors to monitor and automatically apply the brakes to prevent a rear collision. The S5 doesn’t offer backup collision prevention brakes.
The 4 Series Convertible 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 S5’s blind spot costs extra.
To help make backing out of a parking space safer, the 4 Series Convertible 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 S5.
The 4 Series Convertible’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 S5 doesn’t offer a driver alert monitor.
Both the 4 Series Convertible and the S5 have standard driver and passenger frontal airbags, front side-impact airbags, driver and front passenger knee airbags, side-impact head airbags, front and rear seatbelt pretensioners, plastic fuel tanks, 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.